360 engine help

I have a 360 I built I am having issues with and I'm hoping someone can help me figure this out

I built it several years ago and put it in a power wagon. had lots of power, would start in second just by letting off the clutch without touching the accelerator. This was my daily driver for about 2 years. It has MSD 6AL ignition box, coil wires and mechanical distributor. RV cam, Holley vacuum secondary 600 CFM carb, Edelbrock RPM intake, headman headers, and I did a full rebuild with new 30 over pistons and everything.

I started driving a more economical car for a while and came back to it and noticed it wasn't running right it idles just fine but once its put into gear it bogs down really bad at around 1200 RPM then kicks in really strong. If I just rev it in neutral it seems to rev much easier but sometimes hesitates pretty bad.

So to me it sounded like a bad accelerator pump, so I replaced that. Old one looked good, made no difference. Then I rebuilt the whole carb, no difference. New plugs, new fuel... no difference. increased the pump jets in the carb, nothing. I just removed the distributor cap and noticed the little ball at the top was broken. Ah ha, found it! I ordered a replacement cap and... no difference. I just tested compression on all the cylinders and got 135 PSI all around so nothing mechanically wrong. I can't seem to find any vacuum leaks, or timing setting that helps.

I'm hoping someone around here might be able to give me some advice and help me get this engine healthy again.