Thanks for the diagnoses.
I will check the opr, and probably replace; preferrably before I go out of town again (without my car). I will let you know what happens.
ps- I once drove a vw bus around europe and doubt I ever went much over 100 km/hr - my brief times on the autobahns of germany were all spent in the slow lane! As for the value of a real workout for my mercedes (at less then 200 km/hr); how about going over a 9,000 foot high pass, followed by hours of winding steep hilly roads, all at temperatures over 90 F; without trailer of course.