That kinda fits the symptoms- I've been looking more for electical/ ignition problems but its worth checking out. There's supposed to be a code set for low fuel pressure but a mechanic I know said that codes soemtimes don't set for intermittant problems.
Thanks-

There are no trouble codes for low fuel pressure on a 502 MPI. The only way to find out is to check fuel pressure in the fault situation ie when it cuts out

mats: The Merc ECM 3 has code 61: Fuel Presssure High and code 62 Fuel Pressure Low. That's assuming the codes "set" on an intermittent loss. Anyway, my next step is to run it w/ a pressure gauge plugged into the fuel rail-

OK. Your engine is newer than mine:D Wish I had one. Good luck

check all wires and conectors while motor is running by wiggling them Also check alternator