I have a 1991 F150 with a 5.8 liter with 139,000 actual miles. This was my father's old truck that I recently came into. The problem I have is when driving, the engine drops to idle for 1 to 5 seconds and then will come back to running. The tach drops to zero, the volt gauge drops to 12 +/-. I do not have to shift to neutral to crank it back, it just comes back. Sometimes it will backfire when it comes back under power. I replaced some of the vacuum lines and that seemed to help for a short period of time, then the it started getting worse. Here is a list of recent new parts.

Distributor
Plugs
Plug Wires
Ignition Key Switch
Ignition Module on Top of The Steering Column
Coil
Solenoid
Ignition Control Module (on the side of the distributor)
Vacuum Lines (Ones I can get to)
Fuel Filter

 

Have you checked codes?

https://m.youtube.com/watch?v=p04NPv_gXsI

link to check codes

 

In addition to doing the EEC test as recommended, these items could be checked also. You can use a paper clip instead of the jumper in the video.

Distributor timing? Was Spout removed when timed at 10* BTDC

Reconditioned Distributor? New is much better if you can.

New Plug wires not routed properly?

Spark Plugs not checked for proper gap when installed.

ICM color not same as old one?

Enlist help to get all vacuum lines replaced if needed.

 

Mudsport96, I'm familiar with newer models and how to check codes through the OBD. How do you check for codes on this 1991 F150?

 

Just watched the video. Thanks!!!

 

The loss of gauges along with stalling tells me something is loose, power wire to ignition switch or power to coil.

 

Following...

 

I ran a wire from the positive side of the solenoid to the positive side of the coil and still had the same problem.

 

Now I've replaced the MAP Sensor and the Throttle Position Sensor. With some help, I removed the Engine Control Module and discovered three of the small capacitors appeared to be burned or bad. I had those replaced, reinstalled and still no improvements. ANY HELP (Besides TNT) is greatly appreciated!!!!!

 

What codes did you find?

 

If you floor it when it starts cutting out, does it take off and clear out? How does it run when cold?

 

No, if you floor it when it is cut out it will back fire when it comes back to power. It runs and idles fine cold and at running temps minus to stalling back to idle.

 

Over the weekend, I purchase a NEW distributor and had the same results.

 

I bet if you put a new motor in, you'll have the same results.
Keep throwing parts at it, you'll eventually find the problem, or maybe you won't.
If your throwing aftermarket ignition parts at it, you'll probably introduce new problems.

What CODES are stored in the computer?

 

I have a friend with an OBD 1 reader and hope to get the codes pulled tomorrow.