89 k1500 misfire after head gasket

[HeavyChevy443]

Hey so I know there's a ton of posts about this truck having a misfire, but im wondering if my specific situation can narrow down the possibilities, and hopefully save me some money from buying a ton of parts for a truck im just trying to sell.
I blew a head gasket, so I replaced the head as well as the gasket, did a thorough job replacing all the gaskets I could. I also replaced the radiator and flushed the whole coolant system, and made sure I had clean oil in the truck (added oil, ran it, swapped the oil. Repeat). Now I have everything hooked up completely, and I have a weird stumble/misfire. When I idle in park or neutral, it runs fine. When I put it in gear the RPMs drop substantially, and sometimes it shudders like a misfire. My fuel PSI is 10psi while idling in park. The truck is pretty gutless when I drive it and it stumbles on acceleration, but runs at freeway speeds decently. My timing is set to 8deg adv. Oh and I replaced the fuel filter.

I feel like I've narrowed it down to:
Fuel pump
Distributer cap/rotor, wires, and plugs
Maybe vac leak (but I checked thoroughly and couldn't find one)
MAYBE PCV valve???

Can anyone add to or take away from this list?

Thanks!!