Thanks for the response Gene. If I had a leak, would I still see the full turbo pressure at the gauge? ( I don't know where the gauge pressure is tapped) I've checked (removed and individually inspected ) all the hoses and connections from the turbo to the T.B. I think I may have to try to pressure test from one end to the other to be sure. I did something interesting the other day, I changed out the AMM in the evening and reset the mixture. The car test drove like it had never run before (read "like a bat out of hell!"). I was thrilled and thought I had finally found the problem. The next day, It wasn't as strong (it's always been weak in the morning). Since then the performance seems to be changing subtly. I'm wondering if the ECU is changing to adapt to the different AMM signal. I'm going to set it up to be able to swap them out quickly to see if there is any change.