Ok guys, this is driving me crazy, id really appreciate your help. Heres what i got and what ive done so far... 98 silverado 5.7 Vortec 4x4. 2 weeks ago i installed a fuel pump becuase the truck wouldnt run. ran alright for a day or 2 after that, then it started a rough idle. now this is the tricky part. on rainy days it wouldnt start until i added a can of dry gas and waited 15 minutes or so. so i figured water was leaking through the seal on the top of the tank when i put the new fuel pump in so i dropped the tank again, and everythings fine, so that might just be a coincidence. if its cold, like after sitting all night, it will run fine for about 20 minutes then at about 3500rpm start cutting out, and get worse till it gets down to where it will barely idle, If i shut the truck off, if only for 2 seconds, it will run fine for about 1/2 mile then starts cutting out again. this morning i put on a new cap and rotor, plugs, and wires. And it still does it.... any ideas? To sum it up, in the past 2 weeks i put on a new fuel pump, fuel filter, cap, rotor, plugs, and wires and it still cuts out...

 

it could be your fuel injection spider.

 

probably a fuel regulator or a crack in your distributor cap. if it really messes up when its raining.

 

Fuel filter? When was it replaced last? You could have loosened enough crap in there to load it up when you changed the pump.

 

i changed my fuel filter when i replaced the pump... about 2 weeks ago. to everybody else: i really dont think its an ignition problem. It's not missing, its more of a severe bog. I'll be goin along at about 2500rpm and ill hit the gas and it just falls on its face until i let off. Argon: if it is that my cats are plugged, why does it run ok for about 1/2 mile after i shut it off then start it right back up. I dont let it cool or anything. i just turn the key off and start it right back up? Im not doubting you or anything, im gonna knock my cats out, im just curious, I cant take this much longer!!!

 

they don't plug entirely..you shut er off,and it empties..

if you want to make sure,loosen your y pipes at the manifolds and try it as the neighborhood looks on in terror

 

I cleaned my cats out and my truck still runs terrible.. It seems like that warmer it is outside the worse it gets. or maybe thats just because the truck warms up faster.I REALLY need some advice here.. Update of what ive done: new fuel pump, fuel filter, plugs, wires, cap, rotor, knocked out cats. any more ideas?

 

Is it throwing any codes at any time? Also is it by chance losing a little bit of coolant? These motors are infamous for blowing the intake manifold gaskets. If you can think of anything out of the ordinary for the truck, let us know.

 

i think the only code that comes up is the code for the oxygen sensor... it tripped after i put duals on it... if it is the intake gasket, can i spray ether around it while running to see if it revs up?

 

i HAVE seen 02 sensors do as you describe sorta,...but not as severe maybe...try unplugging the sensor your code is for