Recently my truck developed a problem with the engine. When I accelerate the engine stumbles and the truck shakes like mad. Now for the info: 1. It's an '88 350 TBI engine with auto 2. It only happens when the truck is warmed up and at about 25% throttle. If I get on the gas harder then I can power through the rough spot and the truck takes off fine. 3. I already replaced the fuel filter and lines, changed the oil and filter. 4. I watched the injectors while the truck was running and they seemed to be firing perfectly. 5. I'm guessing it's not vacuum issues since it is fine at idle and since it was a problem that came on suddenly and hasn't gotten better or worse with time. Now I just need you guys to vote on ignition problems (distributor, coil, plugs, wires), Throttle Position Sensor or fuel pump so that I know what to replace with the little money I have.