Its a 88 k3500 4x4 with the 454 tbi and when i bought it it sat for two years.I have replaced the fuel pump, distributor, coil, cap, rotor, plugs wires.pretty much everything for a basic tune up and since i got it it seems like its gradually running worse and worse ive messed with timing numerous times hoping thats all it was but ive tried every position it seems like its not firing right and its running rich.it sounds like it idles a little high and it has good power when you first take off but as soon as you gas it it falls flat on its face and doesnt accellerate.I have ran out of ideas somebody told me it could be my knock sensor but i cant even find one on my motor and the guy at advance said it doesnt have one so idk.somebody please help me!

 

I have seen similiar problems with TBI and it ended up being the throttle position sensor being faulty, it was causing a high idle, running rich and just poor driveability

this should be located on the right hand side of the throttle body, when looking at the motor from the front of the truck

 

thanks, do you know a way to test if the tps is bad?

 

Give this a try:

http://www.youtube.com/watch?v=IsX5q...eature=related

 

my dad had the same problem and he took it off and cleaned it with carb cleaner and it worked properly after, worth a shot

 

Check the plug wires to make sure they're plugged in the right order.

 

look for vacuum leak around base of throttle body,just spray some carb clean around it while it is running and listen for changes in rpms