Engine troubles? Help ASAP please.
 

Well the other day I was gettin ready to go out, and go out to my truck, and turn the key, it just spun over, i put the pedal on the floor, and it started right up, but a day or so later, i was drivin down the road at about 30mph, and it just shut off on me, i put it in neutral, then turned the key, started right up. put it back in drive and rode on with no problems. then this morning the same thing happend, except this time i didnt press the pedal, and let go of the key, then tryed again, and it started right up no problem, then comin home from checkers tonight on us1 goin 60mph, it shut off again, i put it in neutral, then turn the key, and it started right up again.

What do you guys think this is? I need help here, I thought maybe IAC, but would that cause it to shut off like that while driving down the road?

also i was at my girlfriends house talkin to her outside for a while, had the truck running, and after about 30 mins of idling it shut off, i turned the key and just spun over, then i tryed again while pressing the pedal to the floor again, and started up, with a big cloud of white smoke, from burned oil(yes my plenum leaks) would this be related?

===EDIT===

Forgot to mention 2000 1500 5.2 4x4 auto

No the plenum isn't causing it to shut off. i would look into your coil. pickup in the distributor, and check your fuel pressure with the truck running.

how would i test the pick up in the dist?

You would have to have it tested at some place like autozone. Either thaqt or get a manual for your truck and follow the procedure for testing it with a multimeter.

oh, alright. so its not the IAC then?

I can't see where it would be as the IAC only controls air flow at idle or when coming off the throttle as if you were coming to a stop light.

ya, true, well i think i might just do a full tune up, cap, rotor, wires, plugs, im lookin into a MSD Street fire Coil as well.

Well since you are going to do a tune up you should read the diy on doing a tune up in referece to how to run your plug wires to prevent cross firing.

where is that diy at, i looked all opver, and couldnt find it.

http://dodgeram.info/tsb/1998/18-48-98/18-48-98.htm

wierd problem , I'd guess Crank , Cam , or throttle sensor , probably the latter if flooring the gas gets it to start