I have a 98 Silverado with 5.7L Vortec. The engine starts fine and after a few min. it stumbles and dies out, then it won't start for about 30 min. I can hear the fuel pump in the tank.

I want to check the fuel pressure next, what should the proper pressure be before start, and when the engine is running.

If the fuel pressure checks out ok, could it be a fuel regualtor problem.

I also just changed the fuel filter.

 

Check your fuel pressure it will rule out a lot of things, also first check for leaks!

 

I agree with Suzuki-Guy, a fuel pressure test is in order.

Is it TBI? Possibly your choke mechanism is stuck in the cold position. A partner of mine recently used a little spray carb cleaner directly into the top of the throttle body and it did a world of good.

Sounds like possibly a vacuum leak which doesn't show up till the engine warms up, make sure all the vacuum hoses to the intake manifold are tight.

Either you've got acute hearing, or that fuel pump may be producing a "death whine". Is it a low hum, or more of a higher pitch? Sometimes, as a pump starts to go, the parts get worn(producing the extra noise) and as the pump wears out it produces less pressure.

 

I tested the pressure, it stays right at 60psi when running. After I shut the vehicle off the pressure stays at about 57 psi. Today I could not get the vehicle to cut out. It wants to run just fine, I drove it around town for about an hour with no problems.

I did change the fuel filter and added some injector cleaner, could this have been the problem?

 

If it 'fixed' the problem, at least temporarily, and it doesn't come back, then I'd say you probably fixed it if its running well.