revs surging

[brogster]

went out for a sunday  morning ride last week, bike not been rode for a wile
 r and notice that the revs  weren't shutting off when the throttle was closed approaching roundabouts traffic lights etc when stopped at junctions bike would sill be reeving at 3000 for a short time before dropping to its normal 1000 tick over,
If you stop the engine then start when warm it will rev at 3000 before settling to normal tick over,
as i headed home bike started running rough/lumpy at junctions traffic lights and by the time i got home lt would not tick over and was revving at 5000 and not dropping,
went and started it this morning started up first time and ticking over at 1000,
cables ok
diaphragm in carbs?
any  suggestions would be much appreciated.

[slappy]

Is the throttle returning correctly, snapping back?

[celticbiker]

What sort of cold start mechanism does it have?

[unfazed]

Check for air leaks, intake manifolds rubbers on vacuum take off point plugs.