As far as idle, I clean the throttle-body and check the iac/idle air control. Intermittent isuues can be hard to track, you have to test when the problem is ongoing. If your dropping a cylinder, do a cylinder balance test, when the problem is ongoing. Killing a cylinder should have an effect on rpms, if you kill a cylinder that has no effect on rpms, start with that cylinder, it is either weak or dead. Spark--fuel compression? If you kill spark, do it quickly, so you don't flood anything.
A vacuum leak can cause a rough idle.
Tuesday, February 15th, 2011 AT 9:08 PM