gavinbr, yes, my MB dealer has said if the replacement of the crankshaft sensor didn't fix the problem they would put the "old" one back in and credit me for the new one - we'll see.
As for finding an independent MB mechanic - I believe I may have found one

I own an independent bookstore and yesterday a customer pulled up in an beautiful "older" 82 MB - as she was paying for her books I asked who did her maintenance - her "ex" husband, who only prefers to work on older MBs. She gave me his numbers - told me to tell him she referred him. So maybe, just maybe I will be able to park my 92 Mazda 929 "hooptie" and go back to driving my "baby"
Oh, and here is an "interesting" story concerning my local MB dealer - in April in Arkansas we had a HUGE hail storm - size of golf balls - my parking light covers were broke. The dealer replaced them - and I took off for California - somewhere in Oklahoma in the middle of the night one of the covers came off - flies right off the car. I had to wait until I got to Vegas to have it replaced. But wait - there's more! After the dealer in Vegas replace the cover and the light bulb - the turn signals wouldn't work - they had put in the wrong bulb!
Maybe, it's time for me to become a little less "mechanically challenged". Although I must say I do know enough to check all the fluids - but then I had a husband who always said "ugh, me man me fix car, you woman you go bake cookies" But I am learning alot by reading this forum daily - thank ya'll