Just quit running...start and idel 3-4- sec. then dies. Ive changed fuel filter, plugs and wires, and new fuel pump... does the same thing. My check engine light has been on for some time now. (o2 sensor) would that be the problem?

Check again piece by piece all that you just replaced to make sure one of then is not faulty from that house.
Check the oxygen sensors
The engine PCM
Catalytic convertor

Wish you luck

odd,usually if a dodge starts then stalls the ballast resistor is bad,just put a jumper wire across the 2 terminals(white cermic block on the firewall,2 wires) if it runs then replace the ballast only other thought is,have an ammeter? check the back of the gauge,sometimes they burn up and kill the whole system.
Don't quite understand why unplugging the Alt. would matter but check these 2 things anyway.

Could be a small amount of rust got into fuel filter from sitting empty, try changing fuel filter before worrying about the fuel pump.Filters could be partly plugged and its always smart to start with the cheaper fixes first.

If your engine light is on, check for codes. Sounds like fuel pump relay.

Still sounds like pump low pressure I had a simular problem & pump fixed it I even changed ceank poss sensor mine is a 94 s-10..

try changing out ignition coil

This sounds llike weak feul pressure, the fuelpump may need replacing, the first thing to do is have the fuel pressure tested and if the pressure is low then have the pump replaced. the pump is located inside the fuel tank and the tank will need to be dropped to replace the pump, good luck ,

check to see if the injectors are working, what engine do you have? and what kind of fuel pressure are you getting? check fuses for the injector circuit, if your fuel pump is working and you know your spark is good, the next thing to check would be the injector system

sounds like you have a clog in your exhaust like a mouse nest or something like that ive had that problem after storing vehicles for season changes

Have u checked for spark? U can pull a plug wire off, install a plug in the wire (saves u from taking a plug out), place plug on metal surface, crank engine while someone watches for a spark. If no spark check coil and ignitor (inside distributor). If u have spark check to see if u have gas making it to plugs. Crank engine over (no more than 10 seconds, give it a 10 second rest, try again for 10 sec. etc, ) After doing this for several minutes, pull a plug and check it--it should be wet from gas. If the plug is dry, u aren't getting gas (change fuel filter, check fuel pump). countrycurt0