2006 Chevrolet Epica

Engine Performance problem
2006 Chevy Epica 4 cyl Automatic 70,000 miles

The MIL sign appears while driving and the accelerator does not function properly though the vehicle moves slowly and then fast later. When I park the vehicle in a parking mode and then change the gear from parking to reverse and then driving, there is a loud sound while moving. After a few hours, the MIL sign again disappears and the vehicle is in a normal condition. I showed the vehicle to one workshop and the mechanic advised me to scan the problem with a computer. Later I checked the outer part of the engine and I could see oil leakage from the gasket. Is this related to the MIL sign? Please advise correctly.
March 28, 2010.

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