Thanks Rob I hadn't thought of thatRobster wrote: Jon - sounds like a carb issue to me. I would check that one of the idle jets aren't blocked with a bit of dirt. It doesn't take much for this to happen. The car will run on idle jets and transfers to main jets at @ 2500-3000 rpm so a blocked idle jet will cause rough running below this and then the car will pick up above 3000rpm. Just be careful that you re-check the ignition timing. Too advanced and it can cause some engine damage if left like it.
I am sure a quick clean of the idle jets will have it running sweetly again.
kind regards
Rob
And yes I was deffo going to redo the timing.
Come to think of it I don't recall seeing a fuel filter in the line, did I miss it? perhaps I should add one.
Jon