Thanks for the advice. I am resolved to take it to the shop on Monday. Pretty much on orders from my wife as I would have to neglect my actual job to continue troubleshooting.
The shop is charging $128 to diagnose the problem. The owner has had a 1994 525it in the past and has given me some valuable time and advice before and did not charge. I gave him a twenty for beer.
This the first time that I have had to admit defeat and take it in. I do like my wife's cooking.
I will post the diagnosis on Monday or Tuesday.