I have a 1997 Pontiac Bonneville SE with 112,000 miles on it the 3.8L EFI engine. When I first start it, the engine idles very roughly (in park) and will accelerate to about 2500 RPM before coming back to normal idle speed. There have also been several times when the engine just died as I drove along. However, it always restarts. I had a mechanic check it (OBD scan), and he recommended changing plug wires, which I did. No help. The engine light still comes on, and the problems persist. This mechanic also suggested the problem may be the camshaft position sensor. It would be nice to have an idea of what the real problem is.