My Dads 92 Bonneville (227,000 miles) that is currently is my garage, awaiting cradle bushings, runs GREAT when cold. No stumble, great accel, etc. No SES light is on, and when I checked with my OBD1 scanner, no codes came up.

Once it hits closed loop (when the t-stat opens), it starts running like crap. It will stumble upon accel, the idle will lope slightly, and the fumes smell very rich. I could barely get the car up the ramps tonight to change the oil. It would chuggle and sputter and I was afraid to give it 'too much gas' as to drive OVER the ramps, but you get where Im going with this... it chuggles really bad under accel but only when HOT.

I turned the car off, took off the air cleaner hose that goes to the air filter, and the throttle body 'smoked' for about 10 minutes!! It smelled like nail polish remover, I dont know if that has any correlation here but the smell took me off guard.

My Dad replaced the MAF about a year ago with a junkyard one. No coolant has disappeared at all and I pulled 3 of the plugs - they are still gapped around 60 thousandths. I replaced the plugs about 2 years ago (he doesnt drive much, LOL) but I cant remember the last time I replaced the plug wires.

Does this sound like a bad MAF? Bad wires?

I'm wondering what'* causing the smoke to come out of your intake and why it smells like nail polish remover???

How come you didn't pull the other 3 plugs? Check for wetness when you do.

Take your air cleaner hose off and open up your throttle body plate, shine a flash light inside. Let us know what you see. We are hoping to NOT find coolant inside.

I will tomorrow. When I took it off earlier, the MAF mesh honeycomb thing was in the way, so I couldnt see past. I tried taking the MAF off completely, but one screw was being stubborn and I didnt feel like stripping the head off.

I maintain the car, and havent added antifreeze ... geesh I dont remember the last time I did. Its right on the FULL mark still... actually alittle above... last time I flushed it I think I overfilled the reservoir just in case the system burped.