I have been unable to find the source of the fuel delivery issue with the 300E, it appears there is an intermittent break in the circuit somewhere. What is puzzling is the car will start and perform normally at times with everything in place (all my testing is using a new fuel pump relay since I had the old one apart.) I am considering buying a new klima relay or take it to a local shop. When I was at the dealer last week to buy some small parts they told me they do not have a klima relay in stock for my car so going to the dealer would be a last resort. I am waiting to hear back from a local shop on whether they have diagnostic equipment to determine the problem.