Hi to all on here, I have a 2000 Pontiac Grand Prix w/ 3.8l motor with an idle issue I've been noticing the past year but have been letting it go (recently started to annoy me more than normal). I noticed the idle jumps around 200 rpms mostly staying within the 600 to 800 rpm range, when in drive and at a stop light I notice it jumps a tad (especially when warmed up to normal operating temperature). I have already took the throttle body out cleaned it down real well with brake parts cleaner (removed MAF sensor first of course), cleaned the butterfly up well along with the IAC valve, replaced the air filter, fuel filter, spark plugs (ac delco iridium), new ac delco spark plug wires.....
I already checked all the vacuum lines around the motor and not finding any leaks or anything out of the norm.....
About a year ago, when replacing the spark plug wires and plugs...i noticed one of the coil packs had a rusty terminal connection on it??? It was coil terminal #2, which I replaced the coil pack with an advance auto parts coil pack (i believe the brand was BWD or something close). Well i pulled the same spark plug wire for #2 cylinder and the year old coil pack is already starting to rust on terminal #2???? What is going on here, anyone ever experience this or have an answer for this issue....I'm thinking this could definitely be the idle bounce issue.
On a side note, there was an aftermarket car starter installed on the car when I purchased it....The daytime running lights were not coming on when they were supposed to and the headlights would sometimes shut off once put in park....after extensive research I found the ignition switch harness was at fault so I replaced it with a junk yard ignition switch harness in good shape. Found the aftermarket car starter wire tapped into the harness, so I removed the car starter wire to the ignition switch harness and took the car starter wire that tapped into one of the fuel injector wires (forget which wire was tapped into) and completely removed the car starter from my car. I don't know if this could be part of the issue or what but just thought it was worth saying....
Somebody please help me figure this out...I always stay up on all maintenance on all my vehicles but this bouncing idle has me stumped....
