Just bought an 85 IROC with the 5.0 TPI, 100k miles. The car had been sitting for 6 months, but the guy said he had this problem before he parked it.

Idling in park the idle will be a little bit rough, but not very noticeable. When the car is in reverse or drive, and im on the brake stopped, the idle is really choppy...missing on a lot of cylinders, but never stalls. While on the gas in reverse or drive, the engine is very strong.

Seems to be a rough idle issue and gets worse while stopped with the car in gear. I dont know anything about the TPI system, but should I be able to fix the problem with a TB and IAC clean, and cap/rotor/plugs/wires? Or am I off track?

Thanks for any help.

 

Bump...

Engine is extremely rough sitting with foot on brake in Drive (or reverse). Accelerating is perfect, idle is smooth for the most part. Have to put the car in neutral at red lights to keep the idle smooth.

Please help, I cant find any other posts like mine on this site.

 

i would start with the trottle positioning sensor when i had it go out on my old toyota i could release the brake and it would stop but then id hit the brake agian and it would start up

 

Mine idles rough in drive sometimes if I'm in a drivethru or at a stoplight , the RPM will kinda jump up and down like it's missing but only does it sometimes , but runs fine when I push the gas