Ok might be a long shot but this one sparked a memory of a problem car that went through 2 dealers and 4 indi's before me . It was a 300e though (same setup) . When it rained the car would do fine but dry it would act up. After 3 hrs with the car I found that the cover plug for the CISe control module was not sealed properly and it had corrosion on terminals when it got damp it would run fine. This control unit is on pass side behind battery, first one is ABS and one in Rear is CISe. Ck it .After I fixed that car the customer gave me a 100.00 gift certificate, LOL he was happy he only paid 3.5 hrs as to he had already sunk 4k in it at dealers and indi's earlier that year. Good luck.