Here'* a new wrinkle - took two 90-degree right hand turns at a good clip a few days ago, and coming out of them the car stumbled and nearly stalled, much like an older carbureted model might do if the float level were low..
Ran just great (even at higher speeds) on straight roads and even on hills, but those quick sharp turns damn near killed the engine.
Put a couple gallons of hi-test in it, could not duplicate the condition (fuel gauge was reading at just below 1/2 when it first stumbled).
Ran fine the next day, but a day later did the same thing again.
This time I filled the tank (hi-test, of course)..
Despite the gauge reading at just below 1/2, the 18-gal tank took 12.5 gals to fill it.

Two things became apparent -
1) The fuel gauge is way off (reads high)
2) When the car is down to about a third of a tank,
it starves for fuel coming out of quick sharp turns.

Again, at around 1/3 of a tank, it runs just great (even at higher speeds) on straight roads and even on hills, but quick, sharp turns seem to starve it for fuel to the point of damn near killing the engine.

Your theories, gentlemen..?

If your gas gage is way off, how do you know you have a 1/3 tank?

The obvious conclusion is the gas is sloshing away from the fuel pickup screen, but if that were the case it would be a design flaw and it would be much more common. The only things I can think of is the gas is actually much lower than you think (fix the level sensor), the fuel pump (which keeps cool by being submerged in gas) is starting to fail, or there might be some sort of restriction on the pickup screen.

But I'm only guessing. Perhaps someone on the forum has some direct experience with this issue.

I think Roy nailed it.

Being a 92, that sending unit is 20 years old if its OEM. Now'* the time to replace it.

Sounds like we're all on the same page..
The ideas expressed above were my thoughts as well.
I wanted to see if others more familiar with these cars agreed,
before I went off on a wild goose chase, wasting time & money..
Thank you

I calculated the problem to be occurring at the 1/3 tank level because the tank is 18 gallons, and it took 12.5 gallons to fill it immediately after the stumbling condition occurred. An 18 gallon tank that required 12 gals to fill it must've had 6 gals still in it, and 6 is 1/3 of 18, so.. the fuel level was at approx 1/3 of a tank when the stumbling occurred, not just below 1/2 tank as the gauge incorrectly indicated (on level ground).

My fuel gauge fluctuates a good bit on all turns, and on any sort of a grade - reads low going downhill, high going uphill, and swings a good bit even on gentle turns; it can swing up to 1/4 tank easily..

Are they all that sensitive to motion..?

Up to 1996, the fuel gauge would fluctuate as the car moved. 1997, the fuel gauge was read by the PCM and compensated for the "slosh" effect, then the signal was sent to the instrument cluster.

With my 95 B-ville, if I was at 1/2 a tank and I romped on it, my gauge would goto full.

They are when the baffles are broken in the gas tank, which is a horridly notorious condition in this generation. 3/8 of a tank is the magic number on mine. Highway on ramps, hard stops, etc, all cause the exact issue you describe in mine. If the gas tank is half full, it takes extremes to replicate the issue, and gets more and more temperamental the lower the fuel level gets.

Also, your fuel sender may not be helping the issue only, but it is not the main culprit. The solution is usually to replace the fuel tank, but I just keep it full of gas.

I like your solution lol.. I've just been filling up whenever it shows 1/2 tank -
No more stumble on sharp, quick turns

I had a similar problem with my 93 Buick LeSabre. It did appear to be related to the fuel pick-up. However, I am not so sure now. Mine would come and go and at times even with a low tank it would not stall when making a sharp turn or quick stop. Then it appeared to stall at times when turning with 1/2 tank. I didn't want to drop the tank because I would have to build a support to use with the jack to lower the tank and disconnect the lines and having to do it all by myself when it would be an easy two person job.

At one point I though the stall on turns was the battery cable/alternator output cable because a battery leak has made the positive cable prone to corrosion. I was using a battery that was a bit larger and thus could not use the hold-down and I was wondering if on turns the battery would shift enough to break electrical feed to the engine.

One time with the stalling I could get the car to stall with a low tank by backing up the slight grade on my drive and hitting the brakes. It seemed to be that the gasoline was sloshing out of the fuel pump pick-up.

This random stall coming and going (I could dive for six months or more with no turn or sudden stop stalling) continued for several years. One time I drove the car for a year without any stalling only to have it return.

Then I had the original problem with my car stalling out and not starting again. I could drive it about six miles and it would stall and not restart. That is where I made the mistake of using one of the answer sites on the net and some guy had me throwing parts at the car without actually telling me how to do tests. In the end I used a high powered magnifier lens and examined the wires on the MAF sensor and noticed that the heated wire one was burnt completely away (you need a strong lens to actually see the wires wound on the element). Replacing the MAF sensor fixed the stalling problem.

Unfortunately, I have not been able to drive the car long enough to see if the MAF sensor was the actual cause of the stalling when making turns. However, I am wondering if that was the case. When we make sharp turns, as in turning into a side street, we let up on the accelerator pedal, and that shutting off of the air vane with a MAF sensor telling the engine wrong information on how much air is coming into the engine along with the idle control motor at whatever position, causes the PCM to not be able to do proper calculations and stalls the engine. Maybe? Something to think about before spending a lot of money on a new fuel pump; you can, by the way, get only the pickup and reuse your pump if the pump is producing enough pressure; and by the way, my pressure supposedly ran a bit lower than the specs but was not an issue.

Right before the stall and not start problem, I had the engine stall out just making a stop. I was at my sister'* house and she had some gasoline and we added it to the tank. It did not make a difference and I had a 1/2 tank. She followed me home and the car stalled at least six or eight times, making a turn, or just stopping at a light or stop sign. The distance between our homes is 18 miles. Then the problem seemed to clear up. Then a week later the stall and not start again until the engine cooled happened.

The more complex they make cars, the more complicated the problems can become..
I have no solution for you, I'm still learning about my Buick and it'* quirks.
Great job documenting your car'* problems though..
Is yours still giving you trouble or has it been resolved?