GMC Sierra 2500 stalls while driving, but usually starts right back up?

As the title says, the 2001 truck has been acting up lately. This usually happens when the truck is in motion, doing about 40 mph or so. It will quit, i have to pull over to the side of the road. And it usually starts right back up. This has been going on ever since I had the fuel pump replaced about 3 months ago or so. It was doing it once every two weeks, then once a week, then once every other day. Then it stranded me at the store before xmas. Right off I thought it is the fuel pump being intermittent, and just getting worse. Im not so sure though. My mechanic will warranty it, but would rather not have to if its not the problem. He would rather have the truck die and stay dead, and test out things from there. There in lies the problem. The pump works, I can hear it power up, and if the truck stalls, it starts right back up. One more thing. If it does not start immediatly, and i dont drain the battery, it will start in an hour or less. It will not just stop working for an extended period of time. There is no check engine light on btw. No codes come up while its on the computer. Anyone with any ideas or who have had a similar problem, let me know. I dont drive it except in the driveway to plow, for fear of having to have it towed. It works though as i have a really long driveway.

Have your mechanic check out the crankshaft position sensor - inspect the wiring and sensor for damage and function. This is classic for that beginning to fail.

A bad CKS should set a code. Has on every car that I’ve worked on. However, a fuel pressure problem has no direct code. Check with your mechanic, and see if he’d be willing to put on a fuel pressure gauge and tape it to the windshield. You can monitor the fuel pressure as the truck stalls again.

I had a code before this happened. It was throwing an EGR code. He discovered it was a cracked mount that the EGR valve is attatched to. He didnt think it would fix the problem, but we went ahead and fixed it anyways, and i have no more codes. Some guys suggested cleaning the MAF with the correct cleaner. Another suggested adding seafoam to the gas and oil, and cleaning the throttle body with TP/Carb spray. Said it cleared up the problem for him. One weird thing that i forgot to mention is sometimes when it stalls the change engine oil light will flash 5 times in pretty rapid succession. The oil has been recently changed though (within 1k miles). I dont know if thats some weird code, but i cant find anything about it.

I’m with @cigroller since the fuel pump was already replaced.

I’m no expert, but I have experienced this a number of times on a 6.5 diesel. I have learned a bit dealing with the nuances of this engine that Chevy don’t provide preventative advice about, but does charge an arm and a leg many times. Here is what I have learned about this subject; the fuel pump power is controlled by the oil pressure switch that provides power to pump fuel only when the engine is running and start-up. The idea being, in an accident, the power to the fuel pump is shutoff. I have replaced the oil pressure switch many times because it can’t handle the amperage. I now have a setup from Kennedy Diesel that bypasses the oil pressure switch for power, but still uses an oil pressure switch to maintain the intended safety function and adds a relay to cut power if needed. I added some additional fittings to make it easier to remove the new oil pressure switch, if needed, but I have never had this problem again.

So, I would replace the switch on your truck and see if the problem goes away.