Misfire at cruise, popping/afterfire at 3000RPM

I apologize for not replying sooner, been busy with other things. The transmission is currently out and the engine tilted back, so I haven't been able to pull the plugs just yet, but I'll get after it when time permits and post pictures.

I haven't done a compression test since the heads came back, but previously I saw numbers between 150-165 psi. I'm not sure if the variances were due to my cheap Chinese compression gauge or user error, or just normal variances in the cylinders. I'll run another test when I pull the plugs.
150-165 I would consider stock reading maybe a littlle on the lower side.
I myself ran into trouble using a chinese compression gauge, dont trust it.
Make sure you have all the plugs out and the carb wired open WOT when you take the new readings.