Hi, my cossie has started to missfire at part throttle and idle really lumpy. It idles better if i dissconnect the ISCV, i have changed EVERY sensor, ecu, loom, plugs, leads, dis cap, rotor arm, last thing left to do is re gasket the plenum/inlet manifold, could this be the root of my problem?

 

give the idle sensor a good clean out and did u use original sensors.