i have an 87' 5.7 L TBI K-5 full size blazer. i fix one problem and run into another. My recent issue is hard for me to explain. While I am driving at around 35 MPH the truck feels like it cannot decide what gear to be in. it jumps back and forth. It seems random but i find that it usually happens when I am going uphill or starting from a stop light. I have changed the distributor cap and rotor, the fuel and transmission filters along with the transmission fluid. The spark plugs are only a year old. My exhaust is non existent if that matters at all. I am hoping somebody can understand this and might have run into the same issue. Any help would be greatly appreciated. My trucks' name is LBADBLU, brother of BBADBLU and it would greatly appreciate it too.