Spoke too soon, went for a ride and symptoms reappeared. Checked intakes seal again (with ether) to be sure beyond a doubt. Pressure tested the fuel pump ...... oh dear. It could build pressure but not keep it up......sounds familiar.
I removed the pump......it's fokn trash!!! Photos to come. If I could I would pass the address of the guy who did this on as he needs bashing. The engineer in me wants him banned for life from touching tools. The Neanderthal in me wants to club him daily for the rest of his life.