My 93 GT has a high idle problem, i have plugged the hole in the butterfly valve which helped lower the idle problem, but the car still randomly idles high, about 1300rpm. I have done all things to help the high idle and nothing has helped, but i have kinda figured the idle problem must be caused by timing advancement by the ECC. Before i plugged the hole in the butterfly valve i checked the timing many times and everytime i checked the timing i unplugged the jumper in the wires connecting to the distributor cap, actually the TFI, and the idle down to the normal 700ish area, and the TFI, to the best of my knowledge, is responsible for advancing the timing. I calibrated the timing to 10 degrees, but adjusting the timing helped nothing, but the idle was in the normal range until i plugged the jumper back in and then the car idled back to 1300rpm. is there a way i can test to find the cause of the advancement problems?