LG25

I have a 2013 Silverado 1500 WT with a 4.3 V6. I have been fighting and engine stall issue for a couple weeks now. Originally I had a P0336 code that would be given when I would get to abour 1500rpm and 55mph. Truck would shake and buck and then go into limp. Changed the crankshaft sensor and the problem persisted. The code changed though to a P0300 so I changed the fuel pump having had some experience with those going bad. 300 dollar lesson later, not the issue. I have ensured the battery is good, MAF is good, not getting any specific cylinder codes so I don't believe it is the plugs/wires. No fuel leaks that I can tell. I checked my throttle body and it seems fine. I'm lost and I don't want to replace another good part. The only feedback I'm getting now is that after about 30 mins of driving the truck will start to stall at low rpm or idle or if I go above 3200rpm. It will also stall out if I put the truck in reverse. No issues at first start.