Well I could rule out rocker cover breather and plugs. Just had two error codes showing two separate miss fires but running ok now. Then drove about 35 miles and low and behold its feckin back. Turned of ignition and back on its gone. No faults on ecu and still does it when I got home. It's like the revs dip below 800 or so then it compensates and pops above 1000 back and forth which sucks. If you sit at a junction and the car lurches forward even when I have the breaks on. It's a bit scary reversing in a space also, this is as intermittent as it gets. Still no fault found not giving in because I actually still love the car. Any other ideas ?.