If your mechanic did not use the S&S Pro Tune diagnostic software first thing, he's not much of a mechanic.
I'm deeply offended by the expensive process of changing components in the hopes that you will stumble on the answer.
The Pro Tune software is free from S&S, all you need is a laptop. It will reveal stored error codes as well as show real-time (while driving) how each sensor is functioning as well at fuel/air ratio, timing, etc.
I think you primary problem is that you have the wrong mechanic.
