I've got 2 427 C5s almost tuned. They both have a fast intake and a 90mm throttle body.
They run perfectly without the AC on. As soon as I put the air on they hang at 2000 rpms while driving. They both idle real well with and without the AC but when you are driving they stick at 2000 rpms. Shut the air off and they go back to normal.
I've hit all the usual tables IAC park, base air, throttle followers in gear and neutral, VE table, timing. This is driving me crazy.
Why only with the AC on is this happenning?