Correct me if I'm wrong, but the return line you're talking about goes back into the injector pump right? The hose is about 8" long right? How would I go about running a line to a container? Do I run one hose from the injector pump into a container and a hose from the metal line into the same container? For the time being, I will replace the 8" hose I'm talking about with clear silicone hose. Also, the original line was brittle/old and tore pretty easy, if it had a pinhole that was sucking air, could that explain my problem?

I also read something about looking for air bubbles in the return line with a clear hose, so I will check for that when I have another set of hands to help keep the truck running.

You might be onto something. I tried blowing through the old hose and very little air came out the other end. Lets hope this solves the issue.

Well, air bubbles came through the return line when cranking and when I finished cranking, they recessed into the return lines. Can upload a video of them recessing and link it if you would like.

edit*

more information: I let the truck sit for a few minutes after cranking and idling. Checked the clear line and there is barely any fuel in the line (about 70% air). Is this a clear indication of a leak in an fuel line?

You need to get the truck running and observe the line for air bubbles-if they are seen while running you have an air leak between the LP and the fuel level in the tank.

I'll work on getting all the lines clear of air so I can get a better reading on the return line. I figured while I was checking the return system, id replace all the return lines from injector to injector as well as on all three ends of the metal pipe. This way I can observe as much as possible.

Really only need to see the line that exits the frt of the IP.

Extra insurance I guess. The old lines were stiff and slightly brittle so I figured why not, couldn't hurt at all.

It won't do any harm at all,just expect to see bubbles exit from the injectors-that's normal.

The rear injectors have plugs on the un-used lines so if you want you could join the 2 rear injectors together with a long line instead of the plugs.

So I can ignore bubbles heading to the IP currently with some air in the lines, but if I see air leave the IP, that's my issue most likely right? Or am I getting something mixed up?

you have the jist of it.