scott rudy

I have a 91 n/a that I converted to a s5 jdmt2 what i am experiencing is a occulting idle and hesitation in acceleration. Note I have all jiving 370#. Initially the engine would go into limp mode when the idle air control valve was plugged in. if i un plug it I can drive it but i experience the occultation in idle & slight hesitation in acceleration. I have not checked the tps. also when I swapped the engine harness i lost some frame systems like ac & wipers & heater. will this affect the ecu? also how can I retrieve fault codes?