Does replacing the TPS require any reprogramming, other than maybe a code reset to turn the SES light off?

No that is P&P.

This morning I thought to check the screws on the TPS to make sure they would loosen up - not frozen. The top screw moved easily with a light twist of the ratchet, like it wasn't even snugged down. I pulled the extension with the Torx bit in it off the ratchet and fit it into the lower screw to make sure I had clearance and enough bite to remove it. Seemed fine, but when I pulled it away to put it back on the ratchet the tip stuck in the screw and the socket pulled away from it (not magnetized) - the bit then dropped straight down and disappeared... somewhere. I couldn't locate it.

I can't find a new bit locally - only regular bits without the security holes - so I have a new set on order.

You will be Ok with it until you get the bit. it won;t hurt to drive it like that.

The TPS is still firmly attached, nothing loose.

I only fitted the bit in the bottom screw for a clearance check - didn't loosen. The top screw I re-tightened after I broke it loose.

We've got a wave of cool front moving through and the outside air temps dropped by 10 degrees. The hesitation problem was almost unnoticeable when I went out this morning.

If and when you do get the TPS off. Make sure you reinstall it properly, otherwise you will have issues afterwards.

I have a video on YT explaining how to reinstall it correctly.

Thanks, Mike. Can you point me to your video..

Fifteen months later . . .

I had to set things aside for a while. The car'* symptoms didn't get worse or better this past year+ except for a new direct replacement Delco battery in Jan 2022.

When I was in a position to go at this problem again, I didn't throw parts at it, nor did I do any testing on my own. Suddenly a few days ago, instead of instantly starting when I turned the ignition, it cranked for 2-3 seconds before starting - never did that before. Then on the road as I was going up a very slight incline, it felt as if the engine started missing - like driving over a washboard surface. That stopped when I reached level ground.

I realized this was a little over my head so I took it into the Buick dealer. They found Codes P0405 & P1440 - EGR sticking. They replaced the valve, gasket and a new set of spark plugs. They also did some cleaning (said they "cleaned the ports"). Well, this little repair seems to have corrected the driveability concern(*) which prompted me to start this thread. Starts and runs smooth as silk. No more throttle problem.

The cost of this repair took a chunk out of my savings - more than the estimated value of the vehicle - but still cheaper than a newer car. It'* got less than 125K on it and has had all fluids flushed and replaced, as well as new front pads/rotors at 50K. Has had regular LOF'* since new. All it needs now is to replace plenum gaskets and one engine mount. I'm hoping this baby will last me for many more years, or until I win the Lottery.

I want to thank all of you who took an interest and offered suggestions/help.

Good news!

Thanks for the update!

I was told the lower intake gasket was leaking oil and there was a small coolant leak. I went ahead and made another appointment to have the intake resealed - not sure yet if they'll do the plenum gaskets too. I think I'll have the front pads and rotors replaced also, it'* been almost 75K since they were last serviced.