Possible bad spark plug wire?

[nleksan]

Glad to hear that the problem is solved. Did you replace the boots when you changed the plugs? Not doing so can cause issues similar to what you have explained, in my experience.

 

[Jimmy9190]

Thanks..I did not have any of the typical plug wire problems. No misfires, no stalling out, no power loss or rough idle. Just the idle fluctuation from about 750 to 850 or 900 RPM and back down again, it happened about once every 10 seconds. I put in a new IAC, it helped but the idle problem persisted. Then I put in a new TPS and the problem is gone. I have a nice even idle now, right where it should be, steady at 700 RPM. I think what happened was my old TPS got wet with TB cleaner spray because I did not remove it from the TB when I cleaned it. I also am pretty sure I ruined my old IAC by pushing and pulling too much on the shaft when I cleaned it. I read online you are not supposed to do that.

The new IAC and TPS brought my idle and throttle response right back to normal. The dead spot at 60 MPH is long gone and the throttle response is nice and crisp. At 162K it was probably time for a new TPS and IAC anyway. The ones I ruined were OE. It did take about 60 miles of driving for my PCM to learn and calibrate the new IAC and TPS. I really thought something was still wrong until I drove the truck to work and back home today. My truck is idling perfectly now and my gas gauge seems to be dropping towards empty at a normal pace again so I am calling it done unless the wonky idle problem returns.