Right im running a 1.8ZVH and ive got a misfire but only when my foot is flat to the floor!

If I hold the car at half throttle say then the mis-fire is still there but no where near as bad and it seems to ref fine.

The misfire is from about 4.5K upwards. Ive already changed the plugs, leads, cap, rotor arm. Tried 3 different fuel pumps (All known to be good) and even run another power feed to the pump just to be sure aswell.

Im only running 14psi and ive got a GRS cooler aswell. The engine has good compression on all cylinders aswell.

I have recently changed the wiring loom in the car as the one previous was a little tired but could the new one be causing the problem?

Was possibly thinking it could be related to the throttle switch maybe??? Anyone else have any ideas?

Getting desperate and dont really have the funds at the moment to take it anywhere!!

So come on people give me some ideas or stuff to look at/check

Thanks in advance

Gary