I got a 95 gmc k2500 6.5L ocasionally does. Most of the time at idle sometimes while driving.When I start it up again it only starts if I push the gas pedal all the way down while cranking for about 10 seconds. Replaced the lift pump, fuel filter and oil pressure sensor (which now is maxed out. Separate issue?) No change yet

 

Pay attention to if it is dying when going uphill. We had the same issue with our 1998 Chevy Suburban K2500 6.5L, and if you have gone through changing everything in the fuel system, next is to rewire everything! And I mean everything. Most of the wiring is exposed to high heat on these engines. If the wiring doesn't fix it, the next place to go to www.dieselplace.com/6.5newbies. This helped us out a lot. There is sometimes issues with clogged or bad radiators and intercoolers.

 

Have you replaced/relocated the PMD yet?

 

It sometimes chugs going up hill. But no more chugging the. Regular hard acceleration.
PMD was replaced when it was relocated when I bought the truck over a year ago. (new location is mounted in the passenger fender

 

Should be mounted OUT of the engine compartment. I bolted mine inside the front bumper with the cooling fins facing outward. If I get a pic I will share.

Has the fuel sending unit been replaced?

Straight wire the lift pump and give us the L/min flow out of the T-valve. Will help to determine if there is a fuel restriction.

 

Forgot to mention within the last few weeks I've noticed when this happens if i bleed the air from the fuel through jumping the wire on the relay. Lots of air comes out. I've replaced the fuel filter, lift pump and the OPS and no change. Any ideas where I would be sucking in air?

 

I would guess you got a clogged fuel sock.

 

But how that lead to air in the fuel?

 

Somehow vacuum pockets will form when the injection+lift pump are pulling from a restriction.