2000 4.2L can't keep it running

Last time I drove the E250 van, it was raining & The van was idling rough. I fugured maybe it had a potentially failing coil, or something electrical. OR maybe the rain was coincidental?

Anyway, Now it won't stay running at all. Initially starts right up, but after 2 seconds, its chugging, & stahls. It will not rev up. turn off the key, & restart, runs pefect for 1-2 seconds again & same thing.

So, I was thinking it was the fuel pump, or relay. But I can here the pump running the whole time the engine is trying to run, once it stahls, I here the fuel pump stop.

The weird thing is, it can be stumbling along, just barely runing, I flip off the switch, start it back up & it revs right up for 1-2 secs. So something changes from start mode, to normal run. I scanned for codes, & there is nothing present except misfire codes.

Thanks in advance, Carl