Starting issues

[tutone]

Hey guys, I usually post in the 67-72 forum because my 98 k1500 is so reliable. As of late , I noticed that it would not spring to life as soon as you hit the key. It has for the 19 years I have owned it. It has started and fizzled out but upon retry, it would be alright and run normally. This week, however, it has not been nearly as intermittant. Almost every time it would flake out on me. I researched and found that the fuel pump comes on, builds pressure, stops, then when it cranks, the oil press switch sends a signal to the fuel pump relay and it starts again.
I suspected a worn op switch, 240xxx miles, so I installed a new one. Now after installation of the new switch, op jumps right up on the factory guage, but now my fuel pump will not shut off. Key off or key on. I checked relays and unseated all of them. Reseated reconnected battery and still, runs all the time.
Im having trouble wrapping my head around a new switch causing that issue. Nothing has ever been hacked on this truck and I have owned since 2003 with 31,500 miles. Have you guys any ideas to try? Thanks