84 c10 Rochester 2 barrel off idle stumble

[Triple6Goat]

Hey guys,
Just picked up a clean rust free 84 c10 that originally came with a 6cyl but was swapped over to a crate GM 350. The swap is clean and looks like it was done some time ago. Anyway, it has a 2 barrel Rochester carb on it. I would love to just rip it off an replace it with a 4 barrel but for now I'd rather drive it as is.

The problem I'm having is an off idle stumble, only under load. I hooked up a vacuum gauge and adjusted both mixture screws properly. I also had to reroute the vacuum lines as they were improperly hooked up. I thought I had the problem solved after doing these two things, but no luck. One thing I didn't do was check timing because I don't have a timing light. Also I don't have a tach hooked up.

Any ideas? I have a 5" autometer tach laying around I might temporarily connect and I'll buy a timing light, but I'm thinking I'll need to rebuild the carb. Also my kick down for the th350 trans doesn't do anything.

Help is appreciated. Cheers!