I have a v6 and one side got oil on the spark plugs. It has rough idle making the rpm needle moving up and down. I think the rough idle is from the EGR valve, but why would oil be on the spark plugs? Could it be a bad gasket?

 

Oil on the porclin part or the actual diode? If its on the porclin then you need to get a valve cover gasket kit(very inexpensive)....If its on the actual diode, then maybe your piston ring(s) are shot... And a bad egr valve can cause really bad idling....

 

diode != electrode

 

It's either your piston rings or your valve guides. Check both. This could also be the reason your idle is bad. Fix problem and check idle afterwards to see if that was the problem. If not, then change egr valve.

 

The check engine light was on at that time too. I finally took it to the dealer and they put a new map sensor on. After driving 1300 miles to Kansas City and back, I'm gonna have to look at the spark plugs again. Seems like the vehicle is eating a little more gas.

 

Possible blown valve gasket or valve seals. Make sure engine oil is not overfilled.