Sputters when accelerating

[MjPioneer]

Odd little problem today, put most of my truck back together and took it for a spin down the block. When accelerating from a stop it will get up to about 7-10mph, or about 1600rpms and it will stall and jerk back to life, almost like it has no air flow, or it's out of fuel. I couldn't get the truck out of 2nd in the area I tested it but it also did it in 2nd but only under heavy acceleration. The truck does not sputter or act different in neutral. I was pretty mad about this but then I remembered a few things that could be contributing to this issue..

 

*intake is not on the truck it is only a throttle body open to the world. Maybe not getting a good air flow?

*before this the truck did run out of gas, I put in about a 1.5gallons though. Perhaps the fuel rail or system has air in it?

*I noticed the truck was running hot at about 215-220 degrees, I remember when my Xj would run hot it would stall. Engine sputtering because of heat?

*since the truck is in its mock up stage there is no exhaust on it, no cat no muffler no nothing after the manifold. Lack of back pressure casing this?

 

I was going to toss more Coolant in the truck, but I have sprung a leak at the thermostat housing so I don't want to risk causing a bigger problem right now. I plan on pulling the housing re-sealing it and burping the system later on today to kill that problem.

 

Any of these things seem like they could do this to a rig? Since I need to tear it apart again I don't want to have to re assemble everything test it then rip it apart, just adding more work you know?