Dodge: 1996 Dodge Ram starting problems., crankshaft sensor, dodge 4x4

Question
I have a 96 Dodge 4X4 with a fuel injected 5.2 liter. It has 270,000 kms and the problem I have with it is getting progressively worse all the time. I have a very hard time starting this vehicle when it is cold out. I have to start the vehicle and then continue to hold my foot on the accelerator to keep it running. This usually lasts for 30 seconds to as long as 2 minutes, depending on how cold it is outside. If I don't have my foot on the accelerator while starting, it refuses to start or the engine will surge and begin to flood then quit running. Once the engine is warmed up, it runs fine. If I plug in the block heater all the time, 95 % of the time it will start up good.I have had the plugs, plug wires,rotor,distributor cap replaced, also had the throttle plates cleaned with no better results. Any suggestions.
Possible fuel pump, oxygen sensor, map sensor, cam sensor, etc.
Please help, because this is getting very annoying.
Thank you,
Al Kryzanowski

Answer
It could be the o2 sensor or the catalytic converter.Did the engine light come on?If it was the crankshaft sensor it would start for a few seconds and then cut off no matter if your foot was on the gas or not!I want another mechanic buddy to read this and give me his knowledge on it, i will respond when i hear from him.Thanks RamMan..