[G500 Reid]

I am going to share this piece of information I have found while trying to diagnose a similar problem in my car. The tempreture sensor located on the top intake pipe for the raiator (it has a 4 pin xlr type connector on it) when it goes bad it send incorrect temp. information to your computer. ie it will run richer on idle to compensate. This part can be purchased at the dealer for 23 dollars. It is a small price to pay. Try this as it has worked for me. I was told all the same BS you got fed re: injectors fuel pumps etc. I went over everything in my fuel system with MB at the dealer. I have a friend there so no money loss. It took about 3 trips to find the problem but all fuel system is working fine. Let me know if this helps...