ok i have a 4.3l TBI that i cannot figure out! the problem is that when the engine warms up it has almast no throttle response unitl the RPM's raise! when its warm from a dead stop when i give it gas it tries to fall on its face and will even backfire through the TB (can this happen?) i ran the codes (the A B test) and came up with the o2, map, vss, and knock sensor, i replaced the o2 sensor since i knew it was bad, checked the codes agai after resetting the computer and all it gave was the 1, 1-2 code. as far as i know that means all is good with the sensors. so why is it still stumbling around?? by the way the speedo does not work this is in a 92' cheyenne and it does not have a cat. any help i can get would be awsome!! thanks

 

ttt

 

Check the tps..
Might be bad..

 

i thought about that could but, would it cause my speedo not to work?

 

i thought about that could but, would it cause my speedo not to work?