I have 1993 F-150 5.8 speed density.Having a problem with my truck. It dies off idle if you goose it off idle the truck will stay running but the air/fuel is way lean and take your foot off the gas the truck will stumble and then die. There is no check engine light. and If I unplug the throttle position sensor the truck will stay running and won't die. I have checked all sensors and wiring. The throttle sensor has 4.99 volts going to it and .80 at idle out of the signal wire.
I have good fuel pressure,no vacuum leaks.
Thanks for your help and input

 

Even though you have no check engine light, try checking for codes anyways.

 

I will check it again, Nothing came up on the KOER or KOEO test when I check it a month-ago.

 

This is really getting frustrating I believe I look over everything that would cause lean condition off idle I tested the wiring,sensors and fuel.The killer is the truck starts and run fine at idle and I did get a spare ECM to try and same thing no change

 

The things that primarily affect fueling are the MAP sensor, Coolant Temperature Sensor and the Air Charge Temperature sensor. The TPS is primarily used for "transients".

Since you swapped the computer and the problem persisted, it's likely to be a sensor issue. Also just to be sure, what is "good" fuel pressure?

 

Fuel is 38/40psi. The thing I don't get is when the truck is running as soon as you touch the gas pedal it dies.Now I restart the truck and unplug the TPS sensor and touch the gas pedal and truck stay running plugged the sensor back in touch the gas pedal truck dies and I replaced the sensor.

 

What happens when you try unplugging the MAP sensor?

 

engine surges runs rough

 

I think you may have a wiring issue with your TPS sensor, but I'm really not sure where to begin.

 

Thats what I was thinking so I have a wire diagram and I've tagged the wires to the ECM I check it once and going to recheck everything again and I check the ground also.This is getting very frustrating.