Had rebuilt engine installed. Engine runs rough when in gear and idiling. Runs fine when driving or idiling while in park. I had the EGR valve changed, both bank 1 and 2 O2 sensors changed, mechanic checked for vacuum leaks, changed fuel injector regulator valve, fuel pump and filter changed, Mechanic has no clue. Currently giving lean code. Any ideas?

Thanks

 

The obvious thing would be to see what fuel trims are coming at when at idle and how they change with increase in engine RPM. Since engine runs fine when driving (engine under load), I would not suspect fuel pump/filter to be a culprit (may have been replaced unnecessary). This points in the direction of a vacuum leak at idle. You said it was checked for vacuum. If your can post the results of the fuel trims it may help to further pinpoint the issue.
Also, search forum for idle re-learn procedure. I'm not 100% certain that this applies to 2002 year model, but at some point the PCM programming was changed and it requires a very specific procedure to re-learn idle speed.

 

Thanks I’ll give a try.

 

I tried the idle relearn procedure. It was a no go. Any other ideas.

 

Borrow a scanner from O'Rilleys (or another similar store) that is capable of reading live data stream from PCM. Check what are the fuel trims at idle (Short Term FT and Long Term FT on both banks). Record the numbers (or take a photo of the graph if able). Then rev up the engine and record/photo those numbers. Post back here.