So I’m scratching my head and puzzled. 17 years of working on vehicles and I’m overlooking or missed something, wanting to pick all the brains here in the forum. My friend calls and asks for a tune up on his burban. He says plugs, wires, rotor, and dist. Cap, oil, and filters. Then he makes the remark that it may need a fuel pump, and definitely wants a new fuel pressure regulator put on. I don’t really question or second guess him.. and he drops his car and leaves. I go to bring it around back to my shop and it takes several spins to get her to crank, I ease around to my shop and it dies. I call him up and he says this trucks been running rough, sometime it gets warm and shuts off and requires some time sitting before it’ll crank back. I had a 0339 and 0336 code, checked the CKP and it seems we have good ground, good voltage, but unsure after testing the signal wire that we have strong current coming to it. I’ve been thru the wires, not extensively but I’ve checked them 2 to 3x and I see no obvious issues in the harness. I do have rat leftovers dropped in the usual places for a farm truck.. my ECT sensor test out good, coil is new, ICM is new, plus all the tune up components. I pulled the plenum a second time and checked the distributor, button is seated right, the distributor top is firmly still fixed to the distributor shaft. Throw some thoughts and ideas at me if you would because I’m about to the point of a new ECM. The odd part is we had fire when it came in, and now No Fire.. smh. Thanks in advance.