You could have many things causing this. I would first check fuel pressure. You should also replace your fuel filter if you havent already done this. I hope this helps as it could be many other things.
Could be a bad water pump.
Possible broken/cracked fuel return line.
No - you do not need to have the truck running.
If your truck is dieseling or running on, it could be that the fuel is too rich. Try using a lower octane of fuel.
Sounds to me like you may have rotted fuel lines.
the oil pressure in the engine rises when the truck is warming up causing the light to show, if continues after the truck has been running, change oil and oil pump.
bad coil? check for spark. make sure your getting power to your coil from ignition.
could be the fuel pump
By running out of it.
It could be the U joints from the transfer case causing the problem.
if it won't start at all after running it could be vapor locked. try opening the gas cap for a minute and see if that works.
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