Nothing to do with the manifold, turns out its the Ignition coil! Broke down on the way to work Friday morning, called the RAC out, one of their subbies came out to me and diagnosed it within 20 mins. Good old boy. Just started getting it out now, power steering res out, coolant expansion off and the battery removed, what a bugger! Just trying to get the cap off the coil now, just in case the new coil comes without one. Any ideas on how the wiring cap comes off? looks like a special tool is needed. the cap is held on the the terminals with a weird nut, needs a pronged screw driver or socket. Never seen one.