Motor turns off

Alright, 2001 galant began shutting off a few months ago. It will run for a bit like normal, then suddenly the motor will just stop running.
When the motor stops, you turn the key to turn it on again and it starts up, the revs go up like it would when you start a car and then it stops running.
You can do this all day. It will turn back on for several seconds and shut off.

Here is the kicker. I discovered that if you depress the gas pedal, rev it up high and turn the key to activate the starter for just a fraction of a second the motor will continue to run for several seconds before stalling again. When you do this the starter will of course chirp/grind because the motor is already running.

There is a notable amount of white vapor/smoke from the tail pipe which for this car is uncommon. The car used to be my daily but has been sitting mostly undriven for the past year accept for weekends and occasional short trips to keep it from sitting too much. I know the white vapor is perhaps indicative of a bad head gasket but I feel that isn't the cause here. I think maybe the IAC is bad or perhaps an ignition short. It has also had a bad cat for nearly 50k miles which I haven't changed because it doesn't bother me, perhaps it is clogged? I have not been able to check it for codes seeing that I do not have an OBD reader. I can't trust it for more than a few minutes and I don't want to get stranded driving it to the store to borrow a code reader. I installed a new outlander intake manifold on it a year before this happened and it was doing great until the coil boots got torn and were shorting out. I fixed that and now this is happening. I did fill it with fresh gas but it hasn't changed the behavior.

I had a similar issue, when my mass airflow sensor was bad. I would say you need to get the codes read, before anything. A code reader is always a useful thing to have on hand, and they are not too expensive at the parts store.

The car started and ran for about an hour! Thats the longest it's run in months. Well I unplugged the cam and crank sensors while it was running and both caused the motor to stall so I'm guessing those are functioning okay. Now I'm wondering if IAC or something else could be the culprit? Bad coil pack?

if you find out the problem let me know i have all brand new parts for great prices

PROBLEM SOLVED: So I found a technical article from Doug the link to the article is here: http://www.justanswer.com/mitsubishi...ide-fire.html#

Armed with this knowledge that a disconnected Cam sensor or Crank sensor causes one coil NOT to spark I knew I was on the right track, I really must thank this article for this information. I was originally setting out to solve a problem where my engine would die 4 seconds after starting, the motor would restart as long as you turn the key before the rpm dropped to 0. So you start the car it revs up and acts like it is going to run only to shut off in a very uniform and constant manor. I knew it was something electrical, I read that the CAM sensor was a main cause of this behavior and rented a code reader from Auto Zone since they let you rent the OBD reader like a tool, free if you return it. Well My code was for Cam sensor. I bought a cam sensor on ebay for 20 bucks! I had forgotten to insert the electrical connector to the new cam sensor all the way, I had gotten carried away during the install and put it back together before I got it fully seated... Well I connected it until it clicked and started the car and it started immediately. If I did not read that when the cam and crank sensors are bad or disconnected in this case it shuts down one of the ignition coil packs I might have assumed the fault was with something other than the cam sensor! ALWAYS REMEMBER TO DOUBLE CHECK YOUR WORK. This is one of the simplest repairs I've ever done on any car, 1 10mm nut screw to remove the sensor! So thanks for the support even though it was limited, it's getting quiet around the 8g section but if some one has this issue hopefully you will find my information useful. Cheers