wingnut2k5

I am having an annoying problem.
Ive got a 1995 Subaru impreza wagon(IMPORT) and after driving for a distance it keeps cutting out as though the ignition key has been turned off.
Sometimes it bursts back into life and other times it dies and i have to stop for a couple of mins then its ok!!

Ive just replaced the plugs witth NGK Iridium BKR7 EIX, replaced the fuel pump with a warlboro type thing and reset the ECU with no faults showing

Its getting to be a pain now and desperatly need to get it sorted as i supposed to be taking the family camping!, and didnt want to spend out loads to get it put on a diagnosics thingy

Any help/advice will be very much appriciated