what is your idle rpm set at?
the other day i was at a tuner's shop, and he had a look on consult, no errors, everything was fine, except the rpm was 750 instead of standard 650. he put it down to 650. the car almost stalled when i drove out, then it was playing up alot on the drive home. i got home, set it back to ~750, no probs.
i'm sure your problem's not that simple. but i didnt expect it to behave like that just because of idle rpm.