That's a possibility, I know the Chevy Duramax doesn't have a inline fuel check valve But I'm not sure about 82 6.2 diesel Might be worth looking into.

Martin from another forum had some good tips to check.
The bleeder screw on the top of the fuel filter housing. I would replace it and the o-ring. 2. The filter housing its self. I have seen them get hair line cracks as well as the seals in the hand pump go bad causing an air leak. Those are the first things I would look at.

 

Hi Glen,
No problem starting at all--she cranks right up--two or three starter turns--every time--
What happens is after a minute, to three or four, is it begins "loping", as if it is starving for fuel. If this happens at a stop, the engine will die--and may, or may not re-start. Shop now says it was a leaking fuel filter--but I have doubts, as it originally was towed to the shop after it died, and they changed the filter--I suspect I had some water, or other "crud", that may have messed up the first, and second filters.
I talked to them yesterday, and discovered that they had ignored my request to drain the water separators, prior to changing the first filter ( claimed that there were "no drains"--told them where to find the petcocks--got a "Oh !") -- they have yet to do so. They promised to do it and let me know what the fuel looks like-- Ron Rich

 

Now it is beginning to sound like a bad injector to me.
If it is loping after a couple of minutes of run time... It could be that your injectors are all operating fine on first start up but one begins to fail after it starts to get hot. During it's loping, is it blowing black smoke? (unburnt fuel from that bad cylinder)

BTW... If a garage didn't do as I asked and wasn't providing the good customer service I demanded... I'd be out of there and on my way to another garage. Garages are too expensive to be treated that way

 

Hi Glen,
Nope--no black smoke--also, if you can force it to run for another few minutes--it will run fine "forever". As for finding another place--no one around here wants to work on it --too old--this is a very respected repair shop--in business a long time, 3 A's approved, that works on commercial trucks (Them thar big ones what goes "chew-chew", when you steps on the brakes). Ron Rich