Forgot to add that when it started the RPMs were really high, above 2k. Stayed that high a long time. I stepped on the brake an put it in D and the RPMs slowed but went right back in neutral. It then slowed somewhat but seemed to go on a hunt. Almost like the ecu was re-learning after all the changes that were made.Head scratcher. The car was sitting in the parking lot of the mechanic for over 3 weeks in below freezing temperatures.
Had it hauled there on a flatbed truck because of the no start issue. Since the weather is getting worse in my area I decided to bring the convertible back home. Mech was too busy to look at it. Just for the sake of it I tried to start it and it fired right up, no problem!!
I guess this means I can't help with your problem....sorry. I was almost hoping they could find something wrong.
Let us know what you find out please. Searching the net sounds like it is a common problem.