Three weeks ago my truck would run perfect for 20 miles then instantly switch to barley running.
Two weeks ago it would run 10 miles, last week run 2 miles then switch.
I have replaced the following parts in this order
1) Fuel pump
2) Throttle position sensor
3) Air flow meter (ohm resistance was not linear, bouncing wildly)
4) Fuel pressure regulator

I replaced the fuel pressure regulator today, ran 7 miles then instatly switch to barley running.
What part does my truck need?
Can the ecm fail intermittently like this?
Thanks for your comments

 

Todays test drove 2 miles then engine switch to barley running.
Installed jumper between B+ and FP, drove 25 miles, truck runs perfect.
Circuit opening relay connects B+ and FP during starting and when air flow meter door opens.

 

Any check engine codes? Even if the light isnt on, there may be codes stored.

When its running bad, peek under and see if the cat is glowing red.

 

My cat is cool as a cucumber resting on the bed.
I removed cat two weeks ago in desperation, not plugged up.

 

Installed fuel pump relay, truck runs good.
Relay hidden behind glove box.
What an ordeal, happy truck is running.