Lack of power (can't accelerate in third gear)

[Lauren Child]

Blimey, I seem to be going from one thing to another on Dolly (FGT F22)

Today I managed to spend a bit of time getting her idling again. She now starts and idles like adream, having previously cleaned all the gunge out of the carb and fuel filter, replaced the cables from the battery, and replaced all the spark plugs.

We took her out for a spin and found her a bit lathargic. She runs OK in first and second gear, but an attempt to start off in second (normally fine) lead to an almost stall, and when I got up to third she wouldn't go any faster.

Has anyone got any thoughts on where to look next?