ok guys im having hell with the tbi unit in my truck.It runs fine under half or heavy throttle but at low rpm like running down the freeway it stutters,hesitates and even backfires it is driving me nuts!!!! im at the point where i just run W.O.T just about all the time.it is also idling like crap too in gear it feels like im running a huge cam but its all stock.i rebuilt the motor about a year ago and have no probs for 20k miles just all the sudden ive changed the fuel filter and even tried another upper tbi i have with new injectors,ran a code check got nothing no ses light either i dont wanna start changing out sensors and still have the same prob.....please help.....Steve

 

ok heres what i just did i had a spare tbi from an old motor i went and got a rebuild kit rebuilt it threw it on and still doing the same.I did notice when i had it running and the breather off that the pass side injector looked like it was streaming more gas than the driver side so i swapped the wires and had the same effect is this normal???? and what on earth is causing the backfire?

 

Have you checked the tps sensor. If they get a dead spot in them it will act wierd. Run fine above or below the bad area un less the bad area is just off idle. Check it with an ohm meter and make sure it has a linear scale with no dead spots anywhere. If thats not the problem someone else will chime in I'm sure.

Steve