This is the second time I've had this problem. The first time I just bought an entire new manifold with sensors and replaced the old one. The good old hunting / wandering / erratic idle. At redlights people looked over at me thinking I was revving on them when I wasn't. The idle fluctuates between 1K and 2K when not on the throttle, and when accelerating, the car gets all jumpy.

At first I thought it was the IACV on the back of the intake manifold. I cleaned this out yesterday and replaced it but the car acted the same. So this morning I went to get some real help from Tom Hornsby. As I pulled up to the shop he immediately heard my car and told me what was wrong, and how to fix it. It was my High Idle Valve, located below the TB. I took it off, took it apart, put a little RTV sealant on the bottom of the white plastic thing inside, and screwed the thing back in [it had backed out on it's own. No more erratic idle and no more me scratching my head trying to trace down some vacuum leak.