[homemade87]

The one thing I always do if I have a problem with the things I have just touched is the common sense approach . In this case wires and plugs and a miss fire . The engine warning light on the dash should be flashing with a dead cylinder , not just on . One thing that can happen is crack a spark plug trying the get the old wires off and not realize it . They can be tough some times . Or the plug wires have a problem .

I would start with this before a fuel pump problem to be a suspect .

Also these newer gm trucks do not monitor fuel pressure or have a sensor . Not sure what your are talking about unless you are talking about the regulator on the fuel rail . Fuel pressure is pretty easy to check with a gauge on the fuel rail .