Will check the actual voltage sometime soon when I find my multimeter!

Unfortunately, the issue is back - sort of. This time there is no stalling but the engine RPMs go up and down on cold mornings and after a few minutes stabilize.

P0101 (MAF sensor performance/range) is a definite with the occasional P0300 random misfire only on cold startups. I haven't gotten anything back about the O2 sensor.

I found a thread where it was a clogged IAC valve (which I will physically take out and clean) and broken air duct which caused the issue. There MAY be an intake gasket leak as that was one of the other causes I found for different engines. I should be able to find out once I take out the plugs.

I'm arranging for a new air duct (current one is torn on the inside, but no holes and not perfectly round anymore as such won't sit correctly over the air filter cover, it'* sealed with duct tape) and MAF sensor to be shipped to me, in the meantime I will take a look at the spark plugs as I still haven't gotten around to those yet, I'll need to get the correct socket and extension for it.

A set of "wobble" type flex spark plug sockets and a "wobble" extension make all the difference in the world. Even a cheep set will work. Especially if you will only use them once or twice.

Sorry for the lack of updates, I haven't really gotten around to doing anything with the car.

Since keeping the car in the garage where it'* marginally warmer, the only code that comes back now is the random misfire - the car "feels" like idles way too low when it'* cold even though I don't think it'* that low - around 1000rpm or so. Fortunately I have not had a single stall condition since I cleaned that sensor no matter where it'* parked.

I'll probably just unplug the MAF sensor again so (hopefully) it won't misfire.

RPH - thanks for the advice, I'll go ahead purchase a set of those!

Alright so I took one spark plug out - cylinder 4 and here'* what it looks like:



Possibly minor carbon fouling? Seems fitting as it was probably driven mostly short distances and the plugs are definitely original to the car as ACDelco hasn't made this particular plug for years.

Importantly, is this severe enough to cause some misfires and the rough idle, or could I be looking at a different set of problems like bad coil packs?

I unplugged the MAF sensor and I got stalling again coming to a stop light but with it plugged in it'* much smoother and no stalling. I honestly can't figure out which combination actually causes the stalling as it'* pretty random.

So just as I was ready to put in the new spark plugs, I decided to check the intake manifold bolts. Sure enough they were completely loose, just barely finger tight. I tightened them up and the problem seems to be gone! Idle is smooth as ever and the tachometer needle remains perfectly still. The car does have its share of noises (an arcing noise and vibration from some sort of hose or wire next to the rear spark plugs) but from what I can see the car warms up much quicker now (took just a few minutes idling in the garage) and the idle is as steady as can be.

Not only that, I found a bunch of random loose white cotton or insulation and what may possibly be poop on top of the intake so I vacummed that out.

In case anyone'* curious, here'* the video that got me thinking as the symptoms were exactly the same as mine:

Thanks for updating us, glad you got the issues figured out and fixed.