This car is really aggravating me!

I have a 2002 buick lesabre and i have replaced everything i can come up with to make my car run. first it was thought to b a MAF or a MAP sensors, replaced both car will still not run unless u have it at 4 rpms and holding pedal down. As soon as u let off gas it will die again. i then had all my fuel pressures ran even the fuel pump itself and all came back good. finally i took it to a chevy dealer and he found the cadillac converter was getting smothered when it got warm and was reading at an 11 on back pressure. had that replaced and it ran GREAT for 15 miles and i parked it at home. 2 hrs later try to start it again and it wont stay running again. The last and final thing was to take it and have all the codes cleared and the only thing its reading is i have a misfire. my question is would the misfire cause all of this and make my car not want to stay running unless i rev it up to 4 rpms?? im lost and have had it to 3 diferent shops and no one can seem to figure it out. im at about 600$ and really need to figure this out can u help??

Check Engine light on?


Get the codes and post them here, otherwise its just a guessing game.

Your misfire may VERY WELL have destroyed the original cat. If you don’t get that corrected, the replacement cat may suffer an early demise.

U replaced, maf, map, cat for 600? Good price on those 3 repairs. U certainly have not spent a LOT of money yet. Car drove fine on trip home. Now it won’t idle?

Isn’t 4 RPMs very high? I guess a Cadillac converter will work on a Buick. (just had to do that). I can’t spell it either without looking it up.

4000 RPMs is high 400rpms is low. Why a Caddy catalytic converter on a Buick?

If 400 RPMs is low, how about 4 RPMs?