Ok i finally got my car running (sierra cosworth L6 ecu stage 1) but it has a horrible hesitation problem under load, it idles perfectly and if i slowly rev its great but if you blip the throttle or floor it it just goes mental, i have changed the following items

Crank sensor
Phase sensor
Dizzy cap & rotor arm
New spark plugs
Timing is ok
all gaps are good

Its driving me insane could anybody help with suggestions! Thanks!