'killing' 91 RS Cav

I purchased a 91 RS-3.1 Cav convertible recently and I'm restoring it as it's a great little ride. As a auto body and paint man for several years, I've completed the body (60 hours) and it is showroom now. It has less than 65K on it and has tons of power but it has one problem I just cannot figure out. Most of the time (not all-about 90%) after it's been driven a few miles when I come to stop it begins idling very roughly (high then low progressively) and kills. It starts quickly but continually does this. It's been tuned up-all new stuff but it didn't cure the problem. Any ideas? I'm putting it in storage as winters here in WI are brutal on cars. This is an Arizona vehicle so no rust anywhere.
Thanks for your advice!
Randy

check for a Vacumm leak. Have you had it scanned for trouble codes? Hows the fuel mileage 28 around town 33to 35 highway ? Welcome to AF

I had that same problem with the 3.1 in an Olds Cutlass. I had 2 bad fuel injectors ??? Good Luck

Hey if it revs up and down like that maybe check out your TPS sensor Throtle postion sensor it maybe sticking after cold idle....hope this helps? any 3.1 TPS will work...worth a shot

When I tuned it, I found one bad vacuum line so I dug out the book, located all of them and replaced them thinking that would do it--no luck. I hadn't thought of the TPS or injectors however (autobody mentality). Sensors scare me! Might be best if I take it in to a small shop nearby for those items. Hate doing so--like restoring the entire car myself but despite what my wife says, I DO recognize my limitations!:evillol: . Thanks for the suggestions--they will save me money and a whole lot of frustration.
PS These 3.1 Cavs get that good a mileage? Wow. My 15-year-old grandaughter has her eye on this one-love does have limits however:grinyes: . Thanks again, gentlemen

If you suspect an injector, just pull the injector wiring connectors off one at a time with the engine running. If you come to one that doesn't affect the engine then that one is a problem. In other words, when you disconnect an injector wiring connector the engine should bog down and run ruff. If it doesn't that injector may be bad. It's a good starting point.

When I tuned it, I found one bad vacuum line so I dug out the book, located all of them and replaced them thinking that would do it--no luck. I hadn't thought of the TPS or injectors however (autobody mentality). Sensors scare me! Might be best if I take it in to a small shop nearby for those items. Hate doing so--like restoring the entire car myself but despite what my wife says, I DO recognize my limitations!:evillol: . Thanks for the suggestions--they will save me money and a whole lot of frustration.
PS These 3.1 Cavs get that good a mileage? Wow. My 15-year-old grandaughter has her eye on this one-love does have limits however:grinyes: . Thanks again, gentlemenI had a `91 Sunbird with the 3.1 MPFI engine it got maybe26 to 28 around town, highway 33 to 35. Good engine ,step on the gas and it would GO!. lots of jam.lol. I was having same problem you described but parked the car and never did try to reslove the problem. Best bet would be to have engine scanned for codes and I hear that`s free south of the border .

Thanks Shakewell
That was a new one for me. I tried it and you were dead on--found two that when I pulled the wires, the engine just kept on running as though nothing was wrong. Any trick to replacing them? I've never done it before. Thanks again...
Randy