HI GRAHAM, again,

Have you had the co%checked, i think last time u said stage 1 chip 15psi boost,
u say the misfire is while reving the engine while under the bonnet, could be throttle switch if tracks, are worn would do it at same revs everytime,this with
other sensors ie map, coolant temp, air temp, to calculate from ecu how much fuel needed, at idle part throttle and full load,2wd check pin 11,+30-, at ecu or on switch 400/600ohms, pin 30+17-,in idle position for test 00,if resistance measured
adjust switch,slacken 2 screws on switch and adjust till no resistance, bitch to get at otherwise replace, volts pin 30+11 ignition on T/Closed 4.5to5.5v, open throttle 0.5v.my diagram shows in throttle switch pin order 30/17/11, but on test is 11/17/30.
so u may need to do a continuity test from t/s to ecu to find the correct location for each wire counting at the ecu plug once u find pin 1 as a starting point if u take the ecu plug, apart they are written in the plug, sounds like co% T/S, MAP,OR VACUUM LEAK, good luck, what are the plugs colour,if u take idle speed control valve plug off, engine warm
what is your base idle speed,(tick over)rpm.

Dave,