Hi Kev,
Whoops, picked up your mail to late, already put the manifold back on .
Customer has also informed me that the vehicle has previously had a serious misfire and some coils were replaced. On checking these the three under the manifold were of a newer part number than the other three, also the plugs on the right bank were of a different type to those on the left! I bought genuine plugs in pretty Jaguar boxes and they were NGKs.
If I've still got problems after this I will check the older coilpacks, possibly knock something up to test them off the car, been meaning to make a tester for coilpacks and injectors for some time, now might be a good time
Thanks for the help, Shaun.