Thanks for the info and links. I had a play around today with the idle base reset. When I bridge the GND and TEN revs increase. I've adjusted the idle adjuster screw anti clockwise (not fully) and the revs have increased but I cannot get it to match the ambient idle (but it's nearer). I've noticed doing this the engine now shakes less but still sounds a bit lumpy from the exhaust. As mentioned I've checked and replaced ecu, cas, engine mounts, wires, plugs. I haven't had a chance to drive it since the change yet but may adjust further if I can but found then whilst the idle screw turned after a point it didn't seem to adjust revs higher.