My wife has and 1985 300tdt that has just developed a run on problem. Haynes says the fuel shut off solenoid needs replacing, but they don't tell me where it is or if I can fix it (or replace it) myself. The local MB shop wants over a day and $300.00. There has to be an easier way out. HELP, this car is so different than my BMW, but I'm going to learn it with everyones help.