Strange Idle Behaviour

[Anker]

And also check for vacuum leaks. They typically have the greatest effect when idling.

[pidj]

Because there was a fair bit of work done (below) I will test for a vac leak. I'm assuming this is a factory installed MAF, so it's either dirty (not cleaned when the work was done) or a clamp was not tightened properly/missed when reinstalling the throttle body and plenum.

"Cabin Air Filter: Inspected and replaced with charcoal embedded Mann filter

Engine: Inspected and replaced Mahle air filter. Hoses and belts inspected for cracks. Oil and oil filter replaced with Hengst filter and Mobil 1 0w40 Synthetic. New drain plug washer installed. Slight oil seapage between transmission and engine. Rear main seal was replaced during IMS retro kit install. Oil filter inspected for debris with none present.

Throttle body: Removed and inspected. Slight residue buildup on butterfly. Throttle body and plenum cleaned inside and out. Computer calibration completed.

Oil/air separator: No abnormal oil residue in throttle body or plenum.

Spark Plugs: Replaced with Bosch 7413 plugs.

Coil pack check: Inspected for cracks.

Engine bay check: Cleaned with damp rag and inspected.
"

[rexcramer]

+1 vacuum leaks. They can cause all sorts of mischief. Do you have any pending codes or is the CEL on?

Originally Posted by Anker

And also check for vacuum leaks. They typically have the greatest effect when idling.