1999 Vauxhall Corsa surging/misifiring under acceleration and high speed

hi there, i have a 1.2 16v vauxhall corsa breeze and ever since i purchased the car over 6 months ago i've had an intermittent problem when acclerating. Sometimes when i accelerate to overtake or just get the revs up the car seems to lurch, stumble, hesitate. as if there is no fuel getting to the injection unit causing it to misfire.
I have replaced the idle control valve, speed potentionmeter, head gasket and ive just purchased a maf and new throttle body housing.
the annoying bit is everytime i take it for a diagnostics it reads no fault codes. however, i do not have a Engine Management Light bulb in the dash, as the person before me had it removed or cut the wires. would this effect the diagnostics readings? its just so frustrating, my fuel consumption is through the roof and sometimes the car judders and stumbles at high speed, around 70mph. It kinda misfires then picks back up, then misfires again and then picks up again.

Any help would be fantastic. because its beginning to give me sleepless nights

HELP Please!!!!