So my problem is a flatspot between 2000 and 2500rpm. It really only seems to occur in 2nd gear (5 spd manual). If I baby the car upto 2000 it will splutter/jerk/shake within this range but if I put my foot down a bit it hesitates for a moment and then I get hit with a surge of power, pretty much like kickdown in an auto.

I've replaced all leads and spark plugs, fuel filter, TPS and cleaned the throttle body. I also have a distributor on the way.

I'm running out of ideas. Is there anyone that has had this problem and has completely fixed it? I hate spending all this money on things that are completely unnecessary. Any ideas/input would be awesome. Cheers.

Try replacing the ignition coil, my EF had a massive flatspot in the same range. I did pretty much the same as you have with plugs and leads etc. Turned out to be the coil(pack in EF/AUs, bit different I know, but the same general idea.)

I'm keen to here the result of this as my parent's AU does this...
Replaced the fuel filter today and haven't really driven it much but it's helped it idle a bit better.