Rough Idle or Bad Miss Help.

Hello to all!!

This will be my first post. I'll try to keep it short. I bought a 1991 Regal GS 3.8L 4 speed auto. I had to sink $1500.00 in repairs right away... buyer beware I guess. I'm not complaning just tring to show a level of frustion. The work done replaced the tires, alternator, battery, starter, front end parts, a new muffler, and the CAT was swapped out for a straight pipe.

Now to my question... LOL sorry about the rant!!!!

The car either has rough idle but running good under load condition, or idle is ok and missing and stuttering under load. These change from time to time with no check engine light... For the life of me I don't know where to start. I'm thinking about the plugs and fuel filter?

If anyone could offer guidance I would appricate it.


Thanks to all who respond!!

Cheers
Pat

Welcome to AF!!

The place to start is with plugs, wires and filters given all the other parts you have replaced. These can account for the rough idling and not cause issues at higher speeds. I would also check the idle air control motor and clean the pintle with throttle body cleaner. You may also want to run some good quality injector cleaner through the tank just to clean the injectors.