Trust me, If I could find a Competent Tech In Lubbock Texas, I would use them in an instant.
The closest Tech is in Midland Texas and they get parts from here in Dallas, Texas. He is the one that said rebuid the entire engine and that would PROBABLY fix it. (Doesn't sound Competent to me)
The tech I do trust, is here in Dallas, I wish this problem had occured while it was here, But I don't want to risk damage having to drive the car to Dallas, then fixing a $30.00 sensor ( I can only wish it's that easy, but with my luck thats all that it is)
I think that once I fax all this info to my Father, Whom I do Trust on my BMW and any of my other cars. I think the suggestions that you have given will put him in the right direction.
I do apprecaite all the input on this forum, and by NO MEANS do I want to imply that having a Mercedes Professional look at it is not worthwhile, It's just not an option I have unless I have the car brought back to Dallas.