Fuel injector problems?

About a month ago while driving on the freeway the engine light came on, and engine started to act funny. If I tried to give it gas to quickly it wouldn't respond, but if I did it slowly ti did ok. Eventually after about two days of driving it carefully the engine started to run better, and the engine light went off. Since then I have had the engine light come on several times and get progressivly worse, and have noticed it that the light tends to come on if I hot rod it a little, then same thing happens a couple days later of taking it easy the light goes off. I did have a chip on it and thought that was causing it so I unhooked it, and about three days later I was driving normall and the light came on then the truck had no throttle response and sounds like its knocking realy hard it only idles and if you give it gas it has no response. I got a tester and it came up with three codes:
1: Fuel pump relay circuit malfunction injectors
2, 3, 5, 8.
2: Fuel rail pressure range/perfromance
3: fuel injector 2 control circuit malfunction
I replaced the fuel pump relay under the hood fuse block and the engine still runs poorly. While the motor is running and I pull off the electrical connector on cylinders 2, 3, 5, and 8 one at a time nothing happens
if I pull off cylinder 1, 4, 6, or 7 one at a time the motor dies the second I pull it off. (Not sure what this meens but tried it anyways). I don't think it's the injectors and the rely is fine any suggestions would be appreciated