96 Olds Cutlass Supreme 3.1 approx 50,000 miles.
Having a problem with this car where when you start it most times in the mornings after sitting all night. It starts and has a rough idle, sometimes a jerky feel to it, and backing out of the driveway in reverse and as soon as you go forward it kind of hesitates then smooths out in a few seconds.
I've had a problem with it not starting twice now and I would assume whatever is causing the above problem is the same issue here. After letting it sit for a bit or giving it gas while starting it fires up then I get the jerky rough idling for a few seconds then smooths out again.
Sometimes the check engine light comes on and a test at autozone always shows a code for the o2 sensor.
I've had this car in the shop twice, once for a complete diagnostic test where I told him about the light coming on and what the test at autozone said. He tested the fuel pump and said it was fine and same for the o2 sensor and other things and everything checked out fine. The only advice he gave me was that the intake manifold gasket had a slow leak and he couldn't tell if it was getting inside or not. He also said that a o2 sensor doesn't go bad then all the sudden is good again, like he said after testing it. He said it did show the o2 error in the computer's history. He said he wouldn't replace the gasket but refered me to someone. This mechanic could't explain the rough start, etc.
This other mechanic which replaced the gasket's for me kept the car for a few days and drove it around to see if he could get the same problems I am having rough start, etc. Never happened to him either. The next day it started again. The leak wasn't getting inside.
This issue doesn't happen everyday but often enough that it needs attention. I don't know what it could be and I can't afford to keep it in the shop if they don't know what's wrong either.
Any ideas? Thanks