2000 E-250 Firing problem

have had trouble with this van a lil while back with it stalling out when you try to come to a complete stop. now the van won't start. would this be a catalytic coverter issue? i'm told it's that, fuel filter, or spark. fuel filter has been replaced, it seems to want to fire, but just won't turn all the way over. any help would be much appreciated...thanks....

ok just to add a little more to this for those who can help. this van had been running fine, yes it would stall out every once in a while when you came to a complete stop, sometimes you could catch it before it would stall and it would lunge forward a lil bit then stop and idle fine. i pulled out of a customers driveway, got the van up to about 35 mph when it started cutting out, i tried to nail the gas some but i got no response what so ever from the accelerator. it stalled to a halt on a side street and wouldn't fire back up. it had plenty of power, it tries to turn over but just won't.......if you need any more info please let me know.

Pull a coil and put a plug in it ground the plug against the block check using insulated pliers for fire.
Use a can of starting fluid and spray in the air inlet to the motor and check if it will fire. Between the air flow meter and engine.

no, don't do what the last guy said.
do you have a check engine light on? try that rout first. if no check engine light then start with the basics, air, fuel, spark. check for fuel pressure with a pressure gauge. fuel pressure should be at least 35psi. then check for spark by installing a spark plug light inline with the plug wire. if non then have someone crank the engine while grounding a spark plug wire on the spark plug(disconnect the spark plug wire and hold it close to the plug with out snapping it in) next, check for proper air flow. this is easier using a scan tool with pid data however you can try a couple things like checking for a grose air leak by inspecting pcv hoses,intake air tubing etc. also try disconnecting the m.a.f. sensor then trying to start the vehicle. actually, try this first because it sounds to me like that is what your problem is.
hope that helps get you started.

just courous, is it only after vehicle has been driven, does it happen while the engine is hot or cold, can you cold start the engine, if so, does it run good or like ship?

guess this post was a little out dated for my response. what was the cause for the problem?