ok here goes. first, good day to everyone and thanks in advance. i have a 91 astro 4.3 tbi, for a while i have had a rough idle so i did major makeover. plugs, cap, rotor, wires, coil, ign module, est, temp sensors, map, tps, iac, all new vacuum lines, pvc, air and fuel filter, egr valve and egr controller. major improvement but still a lil rough so i kept fooling with it and now for some reason i can get it to a good idle {never below a 1000, the computer uses iac to keep it there} but when i put it in gear the computer commands the iac wide open. if i put it back in park sometimes it will command it back down. i have snap on scanner that i am using, it switches between lean and rich but the iac steps remain 70 or above. when i back up fuel and spark it runs even smoother. any suggestions????