Hi, I have an '89 TBI Formula and when I bought my car, It ran 16.2's, shifted firm and barked the tires into 2nd, Now my car shifts way too early at 3/4 throttle, dosent kickdown right and runs 16.8's! I have adjusted the TV (detent) cable many times and have purchased a new one from Gm, STILL no improvements! If anyone has any Ideas please let me know, Thanks, Ben

 

Check your govenor weights. THey are at the back towards the tailshaft on the drivers side under a black bowl shaped cover. Just check to see if they move and are not stuck. This could cause weird shifting.