MK3 escort running an MFI S2 RS Turbo engine and running gear. Its over fuelling, creating a misfire from around 2500 revs upwards through the rev range, belching black smoke out of exhaust and making driving very hard. Idles beautifully, no black smoke or misfires when stood still. When under hard acceleration from standing start it will misfire constantly then all of a sudden pick up when on boost and drive spot on. Under deceleration, it wont pop or misfire until I re-apply the throttle....
I have changed the following:
Swapped metering head for another, no change so refitted old one - no change.
Swapped fuel regulator - no change.
Swapped black fuel ECU -no change.
Checked the cold start valve by unplugging the blue plug - no change.
Fitted new Genuine Ford Cosworth Spark Plugs, Cosworth Group A Coil, Motorsport Development Group A Coil Loom, New Distributor cap, Rotor Arm and HT Leads, new fuel relay and pump, fitted new Intercooler and Boost Hoses.
Had the CO set up when I had my MOT in September, was way over but re-adjusted it to the usual level and then made it slightly rich.
I cant see it being the mixture screw on the Metering head due to it's perfect Idling....

I need a set up but at the moment its virtually undrivable...
Any idea's??