360, idles great stumbles uptop

Howdy, i have a 1976 d100 swap with a 79 360 bored .030 over just swapped from 2 barrel to a 4 barrel intake off of a mid 80's? 360 have a 670 holley street avenger with long tube headers. The issue I'm having is it idles great and runs mostly okay up to about 3000 rpm the start spitting back through the carburetor and it doesnt seem to matter where I set the timing and the vacume gauge seems happy and it starts nice right now. Debating on if I need to rebuild the carburetor not sure if its getting to lean uptop.i got the carb second hand I did set the carb back to factory settings and didn't seem to help much, its pretty clean for the most part inside. So not sure what the plan of action should be next