rough idle problem and can't find solution

Have you checked for vacuum leaks? Has the check engine light come on? Have you tried a fuel injector cleaner? Have you checked fuel pump pressure?

Let me know.

Joe

I purchased an OBD2 3100e to check the engine codes. I replaced the fuel filter and received the following codes P0302, P0113, P0122, and P0511. I don't have the tools to check the fuel pressure.

It sounds like the engine is running rich. Have you checked the O2 sensors?