I have been fighting this truck for awhile now. All fuses good all relays good. problem started with fuel pump going out replaced pump tried to start and would shut down Scanned with Genisys 3 found no relevent codes and live data seems within specs. Tested all sensors both on and off truck all operate within ranges. Changed the following sensors,TPS; ignition module; rotor. Running various tests have determined fuel pressure is good and does not drop off before shut down. I have power to plugs right up until shut down this would eliminate ignition system. Truck has passed all self tests the Genysis is capable of. Really running me nuts now. Swallowed my pride and called the checy dealer they thought the security system was locking me out. Did the key relearn three times with no luck. I had changed out the key lock before but truck had run fine for four months. The truck is hard to startand acts like it is slightly out of time but will crank and run. If it was a diesel I would say it was haveing trouble syncing the cam and crank signals. Thinking along those lines the truck had had a power steering leak soaking everything. I am beginning to wonder if the rubber has become softened and the harmonic balancer may have turned on the bonding ring a few degrees. Either that or the passlock module has died. Any ideas appreciated. I may be an old dog, over 40 years experience but always willing to learn new tricks and diesels are my main skill. Thanks for any ideas.