Fuel Problems

I have a 1996 K1500 Ext cab, and my problem seems to be when I am on the hiway that the truck wants to hesitate during acceleration, but when I let up on the gas pedal it runs fine when I lightly touch the pedal, but when I get it home it will stumble, then when I shut down then wait 5 seconds then start it back up again there is no problem with it when it sits there, I have replaced the pressure regulator 2 days ago, the pressure gauge will read 55 psi when running "it goes to 62 psi when I turn on the key", I can hear the fuel pump running very loudly "on its second pump" I need help to find out what is going on or did someone else have the same problem, I also found out that there is a general recall on the injector sticking closed, I need to know if I have a bad pump, injector or sensor.

did you check fuel filter

did you check fuel filter
I replaced it last week, I also took it back to the dealership this last fri afternoon and had the service manager take a look at it and we took it out for a road test and a few things popped up on his hand held OBDII tester, such as a misfire on 2,5, and 6 Cylinders, the O2 sensor B1 #1 was showing low voltage and the knock sensor was reading very high (204 vice 20), the more and more I keep thinking is that I took the truck to a shop and had the upper intake gaskets replaced because of leaking coolant, and somrting tells me that they had to have taken off the distributor to do that, my question is did they put it back on right? and can this be the reason it is misfiring?