I need help...I have a 71 Jimmy with 350 tbi (factory computer) and 700r4 transmission...33in. tires and 3.73 rear gears. All new drive shafts and output shaft from Advanced Adapters. My problem is when I am doing about 35mph my transmission keeps going into overdrive and then down shifting and then going back to overdrive then down shifting and so on. Someone told me I may need a new computer chip since the 93 Sub it came out of was not setup with 33s and 3.73 gears..can anyone help??