Fresh 360 breaking up at low RPM'S.

So I dropped in my fresh 360 along with a rebuilt 904 and 8 3/4.
My problem is that in idle or when I have it on jack stands it runs great. I can pull rpms and the throttle response in awesome. Now, when I pull it out onto the street I can't pull anything beyond 2500/3000 because it breaks up so bad. I have to let off the gas it regain and basically idle back to my garage. I did have a friend put a gun on it to time but I'm not sure where he locked it in at. Does this sound like a timing or fuel issue?
360
KB 107'S
Comp 508 cam / ported heads / RPM Gap
recurved dist with stock ignition and Accel coil that gets very hot when running


Thanks.