gern blanston

I hope you don't fall asleep before you get to the end of this but it all started several weeks ago when aliens forced me to leave my ignition on overnight. After a jump start in the morning, all I could do was pull into my driveway at idle speed. I later found out I could rev the engine by pressing the accelerator pedal about halfway to the floor. My mechanic(independent) diagnosed it as a bad Throttle Body Accuator. Knowing I didn't want to spend $1500 for a new one, he put a junk yard replacement in, which worked pretty normally uo to about half throttle, at which point it would shut down the engine. I decided to send my original unit to BBA Remanufacturing for a rebuild. After following their installation procedure, the rebuilt unit behaves just like the original one did after the alien attack. So I'm $600-$700 into this problem, and looking for the best way to proceed. The mechanic says he needs better diagnostic information to find the source of the problem. He says he doesn't have access to the same info as Mercedes dealer's mechanics have. My online research shows Mercedes diagnostics available for reasonable daily or weekly fees. Are they worth a try, or is my money better spent on an appointment with the nearest dealer. Sorry for the novel, and thanks in adbvance for any helpful ideas.