Hello and Merry Christmas, I have a 93 park avenue ultra with the Eaton Supercharger. My problem is I have a entermittent rough idle problem. I have installed new plugs, plug wires and a new air filter which was needed. That helped in fuel mileage and acceleration. But did not correct the rough idle which seems to come up after the engine has been running at freeway speed and than making an exit and a stop at a stop light. It isnt there during normal acceleration and crusing speed . Any help would be apprectiated.

I'm sure the gearheads will drop in with their 2 cents anytime now. Untill then, is the CEL on? I would try cleaning the Idle Air Control, it'* one of the sensors located in the TB

Start with checking the EGR and PCV valves, also clean the throttle body.

No CEL, I'll give your suggestions a try. Thanks