I have also been suffering these problems on my '94 E420 for sometime now. SRS light on for no reason, Idle speed jumping up and down, no throttle response when I need it most. LOOK OUT FOR THAT TRAIN!! Lastnight I got fed up with it and decided check all grounds I could get to. What I found was all the wires that run in a plastic channel along the top of the fuel rail were cracked. Easy fix as soon as I can get my hands on a new harness. Does MercedesShop.com carry these harnesses? It's the one that runs from a clamp down coupling behind the battery size computer housing through the secondary firewall to the injectors, idle speed accuator, coolant sensor and various sensors atop the engine. I hope replacing this will solve all these problems.
P.O Box 3600
37347 U.S 6, Suite 110
Avon, CO 81620
[This message has been edited by jkurtz (edited 02-06-2000).]