95 Park Avenue Tach is sporatic and engine seems like misfire but recovers. Only does it when it feels like it and is not constant. Doesn't matter if at idle or driving down the road. All of a sudden starts bucking and jerking. Replaced ICM, coil packs, plugs, cam sensor and still having problems. Check engine does not lite when symptomatic.

Could be a coil breaking down , you did replace them did you ? Take a spray bottle of water an spray the coils , mite find cause of the misfire . Also look at coils for a discoloration , a rainbow affect . Or you can power brake the vehicle an take a test light an put neg . clamp end on battery neg . an then move the point end around the coils .

I, feel sorry for you, after reading your problem, but don't worry you visit the Reliable-Store they will help you for sure.
Best Manuals

If the left signal light is affected as well then the flasher can is faulty.
The flasher can is located under the dash.

Do you have cruise control,see if that cable somehow is giving slack,This is a problem with Hyundai where the cable affects TPS plausibility,There was a TSB bulletin by Hyundai Engine RPM fluctuation - cruise control cable adjustment procedure

It seems that correct amount of fuel is not being supplied to the engine. Most probably the fuel nozzles have accumulated some dirt. Try spraying some carb cleaner into the air intake assembly when the engine is idling. This ought to mix with the air-fuel mixture being injected into the cylinders and if the nozzles are narrowed, should clean them up.

change plugs and wires

probly need whole instrument cluster redun or it cud be a module--how important is a tach to you-goin to the drags--a scanner can tell u the rpms if u need engine work

I have had the almost same problem twice. A 'thump', like the engine missed a fire and tach drops. Seems OK after restart. Electrical? Timing chain slip?
Has 135,000 mile. Any clues?

Get a replacement ac control head.