Well, my pot checked out OK. Any idea of the mileage when they typicaly are suspect?

I think I may have solved my idle issue. I was tracking down why my seat belt presenters didn't work. One side the module didn't work and I opened it and replaced a corroded spring and contacts to get it working. The other side was traced to seat belt switch conatcts not opening. When I removed the seat to fix the seat belt switch I noticed the vacuum line to my seat back locks that had become disconnected.

So with one repair I fixed my seat belt presenters, my seat back locks and my hunting idle. I'm on a roll!

PS. I've worked on a lot of cars in my life but the fit and finish of these Merc pieces are a true joy. Things just fit.