Although I had only minor idle problems, there are two plasic accordian tubes, about 1/2" to 3/4" diameter on the fire wall. One plugs into the intake manifold & the other to some device on the fire wall. I found a crack/hole in one of those - on the inside part of a bend. I never would have found those holes unless I was specifically looking for them. In fact, I did miss them on the first inspections. I replaced them with regular old vac tubing. It helped the idle & also got rid of my lean code.
