Tore it down and think I might have found a major part of the issue. There's a deep scratch in both the piston and sleeve. Got it running pretty good for now by just removing one shim from the head during reassembly(came with 3 from the factory, so has 2 now). The new piston, sleeve, and conrod should be here Friday, so that should be that. Didn't do any sealing on the engine during reassembly, but it seems to be running much better. I did however apply some castor oil to all the bearing points and the mating surfaces on the back of the engine, as well as to the piston and sleeve(hate starting an engine dry).
Once I get the parts, I'll do the same thing, oil all bearing points during assembly, as well as on the piston and sleeve. Only reason I chose castor oil is that it's used in nitro fuels, so it should be good for startup lubrication for the breakin.