Modern Vespa

Hi everyone took my lml 2t out today for a blast for an hour or so it ran brilliantly untill I stopped at me mates for a brew....... 15 mins later kicked scooter up and it just died on me and wouldn't kick so used the eleccy start and it fired up and seemed to tick over ok, set off down the road and it felt like it was holding back not revving properly into second gear same problem but then every now and then away it went as normal.
When stationary in traffic in neutral it would tick over and rev OK as soon as in gear riding again same problem, got me home but something not right......

Any ideas what could be wrong or potentially going wrong before it gets too late?

Thanks in advance Alex.

Start with the simple stuff, check you haven't got any crap in the Jets, check for any loose wires, including the spark plug lead, vibration could be causing an intermittent connection.