Ive got a 1992 5.0 automatic and it stumbles when idling or driving doesnt seem to make a difference when its hot or cold.ive put new plugs and wires ,rotor cap and button ,fuel regulator and checked timing and still no difference.scanned codes and it gives 173 running rich.

thanks,bobby

 

one or more of your fuel injectors maybe malfunctioning and stuck on fully open causing the rich mixture. I would suggest replacing them. Also if you throttle position sensor is broken and sends a signal to computer its fully open it will open injectors up all the way and send alot of fuel into engine causing it to run rough. You may want to try this first as it is cheaper.

 

Do a compression test! All the plugs and wires won't make an engine run right if a cylinder or cylinders are weak. If readings are all with in 10% of each other, then pull wires one at a time to isolate which cylinder is missing. Do the same thing by disconnecting each injector.