Every once in a great while, always when idling for long periods, my 240 just dies without warning. It will be idling perfectly normally but just cuts out, sometimes it will almost die but settle down, these times it's accompanied by a quick surge and drop in RPM's. When it does stall it always starts up immediately and runs as if nothing happened. I thought I'd solved the problem I noticed a cracked vacuum hose from the canister to throttle body but no such luck. Idle valve and throttle body were recently cleaned. Plugs, cap, rotor, plug wires etc. have all been replaced recently.

Thanks in advance

K Swan