OK, truck problems

[70cst10_05]

Ok, so heres the deal, a couple weeks ago im comin home from a 20 mile 1 way trip, and the truck starts popping, sounds like a backfire from carb ors omethin, but its not, and it will barely pull itself over 40 mph, well i pull into town, and stop at a stop sign and it dies, really hard to start....it turns and turns and turns, finally fires and i gotta struggle to keep it running. so i get it home park it and go out later and its fine, then couple days later does it again, then stops, meanwhile this popping is continuing, not as bad, but at high rpms, liek when you rap it out or try to go down a highway, then tonight im drivin and it dies really hard to start again, get it started go downtown, dies, won't start. so me and a buddy push it into a lot and let it set for a while come back, it just turns over turns over turns over, nothing, what do you think any of that is???sorry for hte long post, but i need help, its startin to make me mad, i thought maybe fuel pump???i already changed filter..
thanks,
kevin