Have a 1986 f-150 4x4 5.0 302 automatic....power cuts out but engine still running but will not idle up s hift to neutral then back to drive starts to accelerate but starts cutting out continuously shift back to neutral turn engine off recrank everything is fine until it starts again might be a couple minutes sometimes might go a hour before it happens again any ideas or help

 

What kind of maintenance has been done to the vehicle , say last 6 months?
Believe this vehicle is not fuel injected or is it?
How many miles on the clock?
What have you tried so far?

 

Yes it is fuel injected and 249000 and change all regular maintenance is done to the truck plugs, wires, oil and filters other things new fuel relay, water pump, timing chain and gear, master cylinder, brake booster, thermostat, calipers and pads and rebuilt front end hub to hub and the center chunk even though some of that isn't engine related also daily driver so I don't abuse the truck like four wheeling im thinking couple more sensors throttle sensor or cam position sensor maybe even the voltage regulator

 

I don't want to give you a list of possibles and then have you go replacing good parts.
My thoughts so far cover the following; which should be checked and confirmed before replacing.
Ign switch
Coil
Fuel pump connections
Fuel pump if it has never been replaced
What about the fuel filter ?
You must be doing something right to get that many miles .
Does this truck have 2 fuel tanks?

 

Coil, ICM (Ignition Control Module), TFI (Thick Film Ignition) module are a few other possibilities. Make sure you have good clean grounds mainly on the ICM. The coil could be tired and starting to break down when getting hot. TFI's were more of an issue in the early 1990's while they were used due to their location.

 

it has one fuel tank doesn't have any problems cranking just when driving but when the power cuts out the engine keeps running just doesn't idle up if I hit the gas only after shifting to neutral will it idle up that is why I didn't figure fuel problems but will check

 

Great post common.

 

I think now I can follow why you suspect the voltage regulator. If charging output is low or insufficient everything suffers until you rev up the engine and that is why you should check all the grounds as Use Common Sense suggested. Power loss can be caused by poor ign syst output or not enough fuel to meet demand. The fact that the problem comes and goes is what is going to take some time to chase it down.

 

had not thought about the tfi module but have the others and even the switch used electrical contact cleaner on connections also will look into the tfi module thank you

 

.......ok thank you guys for the info couple new things I didn't consider but will try