it runs really bad

Have you changed the fuel filter? If not, do so, and make sure that none of the lines coming from the tank are kinked or anything.

https://www.2carpros.com/articles/how-to-change-a-fuel-filter

The filter in your truck should be under the car, on the driver's side, attached to a frame rail.

I did.

It is weird because once we put the tank back on and cranked it up it was running fine, but it is raining really really bad so I am not sure if it has something to do with the rain and the next day was running bad.

Well there could be a lot of things going on that cause this. Without any codes diagnosis won't be easy. I'd start with checking that fuel pump. If it's an aftermarket pump (like most of what you get at the auto parts shops) then it could be faulty out of the box. I've seen that happen myself, so it wouldn't surprise me. Get the fuel pressure checked following this guide: https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator. Let us know.

Pressure is good. Could it be a bad fuel injecter

Possibly. But on most V8's one bad injector would not make the engine run so terribly like you describe. Yes, you would notice a misfire and maybe even some hesitation, but it would keep running in a decently reliable manner. Out of curiosity, what is the pressure reading? Should be between 242-310 Kpa (30 to 45 PSI) with the key on and engine off or between 193-310 Kpa (28 to 45 PSI)with the engine idling.

Pressure is fine i have had three different people test it.

Yes decently. When i push the gas it is rough until it hits like 10 to 15 mph then stops until about 45 mph it start running rough again.

Okay, I would start with checking the fuel pressure regulator then. Again refer to this article. https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator. Let us know.

Will do.

Please let us know what you find.

Cheers, Ken