problem with iveco daily ?

problem with fuel ?
can go for miles then cuts out turn key off then on whilst still in gear starts going again.
can do this for weeks then it will pack up altogether turn key start for a few seconds then stop.
last time i was broke down for 2 hours the AA couldnt fix it as i waited for the relay i thought id try to start it it started
and run it has cut out since and turned key on and off and got going again
there is air coming yhrough the pipe from the tank