I've been having a weird idle problem for quite a while now. A few times I thought the problem was linked to a vacuum problem and fixed but after a while the problem comes back.

The car idles normally at 900 rpm. Quite often (about 40% of the time) when I go to engage the clutch in 1st gear the idle will drop to 500 rpm, and the oil pressure needle will drop with it from just below the halfway mark to the quarter mark, resulting in a rough take off.

Other symptoms include the car idling high when still in motion with the car in neutral (higher than normal) and very often the rpms drop when the car is in neutral and coming to a stop as if the car is about to stall.

I've banged my head against the wall many a times because of this and am now out of ideas. Any help you guys can provide would be appreciated.

'99 SS