Ideally... find someone who knows what they are doing and get it plugged in.
There could be a few things that affect pull away including a failed Air Flow Meter, and low fuel pressure. Most things can be quickly ruled out with the correct diagnostic equipment.
In all honesty, I doubt even a failed injector harness would cause poor pull away.
Only once everything is working correctly would I consider a remap (as mentioned by Ricky, earlier maps can be slightly a lethargic)
If you wanted a drive down the M1 I'd happily take a look - but if you want someone closer, I would happily recommend Pete Bell (
http://www.bellautoservices.co.uk) - just mention my name.
Ian