dead spot in revs.

[Lumpy]

The carb is changing over from one set of jets to another at that rev range point and it only takes very slight pressure change from dirty air filter to mess it up totally.  Once you get the revs higher it will be running slightly rich but not enough to give misfires or significant power loss

it's definitely not happy and if the air filter doesn't help matters I shall swap it for another TPS I know is okay. I may try the iridium plugs I swapped out last time for normal 9Es too. I know NGK state 8Es but some recommended 9s