Workin on a friends Cavalier and for the life of me can't figure out what's wrong with it, here's the info:

The car idles extremely rough. Pushing the gas pedal past half way doesn't make the car accelerate any. The fastest the car will go is about 60 mph, and can barely make it up a hill. Problem happened suddenly while driving. Oil pressure light comes on at idle even thought it has oil, light goes off while driving. I believe this is due to gas getting into the oil and thinning it out. Burns TONS of fuel.

1996 manual 2.2L OHV
Intake manifold vacuum: 13inhg
Cylinder pressure: 150psi all four cylinders
Exhaust analysis, HC's off the chart
Brand new plugs and wires
3 of the plugs look normal, cyl 4 has a slight white color to the ground

Any idea to what it is and how to test for what it may be?:banghead:

check for a vacuum leak and a big one.

vac leak and 02 sensor are the first two things that came to mind....the vaccuum seems really low though....my GSR pulls 22in/hg at idle