Hard starts and chugging

[72_Chevy_Cos]

This may be redundant, but my truck is chugging. I but it in a town about 70 miles from me and for the first 50 coming home, it ran fine. The last 20 I couldn't get any faster than 45, then eventually I couldn't get past 35. It's a straight 6, 3 on the tree. I finally got it home and now I can't get it out of first gear which is crazy because I can go balls to the wall in first gear but as soon as I shift to second, it jerks real bad and dies out, then it's really hard to start. I took out both fuel filters and cleaned them to no avail. Any help is appreciated!