350 EXCF cutting out (2015)

Hi folks. Can anyone shed any light on this at all please ??
The bike has been bullet proof since I got it but a few races ago it started cutting out a few times during races/rides. (At pretty much idle or very slow speeds) It always started straight away though. During a few quick checks I found the air filter full of crap etc so i cleaned that out and thought Id solved the slight mystery. I then had a practice session on the bike, and it went fine, and I never thought about it again. However, yday in a race, it stalled again and simply wouldnt start this time. (Ten minutes into a 3 hour event . .Race over !!)

Simple things first . . .the plug seems ok, and the inline and intank fuel filter seems ok, although after 44 hours I will renew these anyway.

Over and above those two, what else should I look at ? All Elec connectors seem to be ok too. Kill switch is ok etc etc but as its EFI I really dont where to go next to do checks

Can anyone help at all please ??
Thanks guys