2001 silverado 5.3 missing when pedal is depressed

[Daner]

Hello everyone.

Here is the story.

Go out to move the truck so I can mow the lawn. It starts but it is missing and shaking idle about 3-400. I messed around with the throttle for a while and it seemed to come out of it while idling. Now any push on the gas and it starts missing and will keep missing until I let off. I can feather it up to higher rpms and it will run fine but any semi quick throttle application almost kills it.

It has a new fuel pump 15k ago and basically haven't done anything to it since I bought it besides reg maintenance about 35k ago. Truck has around 136k miles on it.

One other thing to mention somebody just filled the tank up with gas it was less than a 1/4 tank last time I drove it.

I'm going out to do some more troubleshooting now.