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3.3 GM V-6 rough idle

I have a 92’ Century w/107 K miles that has a medium rough idle. This is a summer use vehicle for me. I have done the normal maintenance on this motor w/ new plugs and a good Napa wire set. Any bad vacume lines that I can get at have been replaced including the vacume tree on top of the motor. Has anybody had coil issues or ground issues with this motor? A little help needed…
C. W.

This car should have coil packs, one pack for 2 cyls… yes they can fail, but so can the ignition module under the coils. Is the car throwing a code?? Have you had the fuel system checked for proper pressure, its possible you have a weak pump, clogged filter, dirty injector…etc… It’s also possible that the wires are bad just from sitting (start the car at night and look for blue arcing around the boots and wires…

I guess what I am saying is there is not enough info to really be much of a help right now. We need more details to be able to help…

As gsragtop suggests you need to just stick with normal basic stuff first. Check the fuel pressure. It sounds like your search for vacuum leaks was visual. A vacuum gauge can be very handy. You can also feed carb cleaner or similar around the vacuum connections and intake manifold. I like to use an unlit propane torch. I think the car has a MAF sensor. You should clean it. Also clean the throttle body and IAC valve. While the intake snorkel is off inspect it carefully - poke and prod and bend looking for hidden cracks and splits. It sits all winter? How old is that gasoline? Maybe dump a can of seafoam and a fresh 5 gallons or so in there.

None of the above things are very costly or time consuming. They are all also just good maintenance even if they don’t help. So that’s why they’re good things to just start on before you go chasing other things.

Asking whether anyone has had coil/ground issues with a car this old is a little odd. Any car this old (and certainly younger!) can have those issues.

Is there a check engine light?