The turbo on my '98 C250 TD isn't working. No obvious leaks or funny noises, no lights on the dashboard. The car doesn't have a MAF, it does have a MAP. Took off the undertray & examined the two soft connecting pipes on the intake system, they seem fine. Next place to try is the EGR valve. 2 questions: 1) Will I need a new gasket? 2) Can I use isopropyl alcohol to clean the EGR valve? Actually 3 questions. If it isn't the EGR, what's the next thing in line to try? TIA.