Accelerating issues.

Hi, My cars a 1982 tintop with a 1.3 polo gt engine conversion. Recently (along with cutting out on approach to junctions, found out its the fuel pump or relay) it's been accelerating badly sometimes pulling backward and forward, not accelerating for a second or two or julting when accelerating. It's getting more of a problem and becoming quite concerning. any ideas? Could it be related to the fuel pump issue or could this be dirt in the throttle body?

Thanks. 

if you suspect the fuel pump or relay its probably causing the other problems as well, so get that sorted

main thing is if you have used the polo fuel pump make sure it also ghas the plastic swirl pot and the lift pump inside the tank, without these the main pump will eventually die