I can speak only to the drivetrain...it's essentially the same as that in my '92 500E. I'd have someone experienced take a good look at your monobelt tensioner; they die eventually but are reasonably cheap to replace. Distributor caps ever done? Brake fluid & coolant changes? Lastly, I'd post & inquire if anyone has an easy way to check your timing chain guide rails?
Do your oil changes, stay on the maintenance, and it'll go as long as gas is available. Nice car, BTW.
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car