I brought it back to the mechanic. He said there was a frame rail high pressure pump they missed when they changed the fuel pumps in the tanks. (Two low pressure pumps in the tank and on high pressure further along.)
I take it for a drive and it feels good and strong. When I get less than 5 miles it starts to cut out. I feather the gas and get it to light up again and I have to question whether it is going to die or not. I pull onto side streets where I can drive it and not block traffic. A mile or two later it cuts out completely and nothing I can do will keep it running.
It occurs to me that I should try the other tank. I flip the switch on the dash, turn the key and it starts right up. I think I found the problem. I try the first tank again and it dies again. I try the second tank and it recovers again. I think I found the problem. One of the low pressure pumps we just put in was bad. Now on the way back to the shop I try it one last time to be sure this is the problem. I switch back to the first tank, it cuts out in a few minutes, but this time switching back doesn't work. WTF!
Tonight I reread the manual and now see the wisdom of using the bleeder mentioned earlier to drain the fuel rail. I don't know if I am dealing with an over pressure problem or an under pressure problem.
Could this be an electrical problem in the computer or relay? We did change the fuel pressure regulator.

 

Sounds like a bad Ignition module or a bad coil.

 

If your engine grounds are bad that will take out ignition modules

 

That is something I hadn't thought about. I also have been wondering if the wiring may be the problem even thought it appears to be fuel. Like is the computer not giving proper signals or something like that. I iwll check the grounds and see.

When it last broke down I removed the connection to the thermal sensor. That did nothing. I wonder if by dissconnecting it, it did the same as a faulty reading?

 

We need to reel ya back in. Often when trouble shooting we get so involved we forget to go back to the basics so we dont chase our tails...Ask how I learned this.
When the problem occurs do you still have spark and fuel? If you can answer these two Qs it will lead you to the root cause faster and easier, read less frustration.

 

The next time out I will make a specific check of it. However on the last time out I do know the fuel rail was full of gas. When I hit the shreader valve it sprayed out everywhere. I did not check the spark and probably could have figured a way to do it but I was by myself.