AC spark retard?

[GMCtrk]

My truck feels like it misses on the highway...and it ONLY happens when the AC or fan w/inside recirculate is on. Some one told me that the computer pulls timing when the AC compressor is on. Is there any way in EFI live to disable this? And also, why does it do it in the first place? It is really annoying. I never recall my truck doing it before I started modding it and using different than the original stock tune. Thanks.

[69camaro5speed]

Yes they pull timing out so its eazyer on ac clutches when it kicks in then brings it back up, so if your compresser kicks on and off it will be doing it each time,If you have headers and a cam seems like you end up putting some timing in it,so when that compresser kicks on (with stock timing tables )and pulls timing it doesnt like it with headers and cam,also i had a truck with a bad compresser that part throttle made noise and made the knock sences go crazy pulling timing out lost like 4 miles to gallion ran like really bad,there is some tables that i changed to help this from what i can remember not sure where it was