Bulk head connection issues

Engine looses power every once in a while, wiggle the bulk head connector and its good again wanna just get this fixed once and for all, ignition circut wires have corrosion in them and the connectors are pretty gross too, whats the better option? Buy a new harness and connector and just replace or try to just replace the offending wires myself? If i go with the latter what gauge wires do i need and where to i buy them?