On a recent drive towing a small U-Haul trailer (had a small piano inside) at around 450 miles (for the day) I got the flashing "preheating indicator light for diesel engine" & a loss in power. I was on an interstate highway, climbing a grade, made it to the next off ramp & stopped. I shut the car off, let it sit for a few minutes, restarted & it ran fine so continued the next 150 miles to destination. This has happened twice & at 450 miles +/- 20 miles each time. The car has 116,000+ miles on it. Is there a 3.0l diesel expert out there who can shed some light on the problem? My local "European Car Specialist" (who used to work on our MBZ 420) doesn't work on diesels because he doesn't have the special tools necessary.