This might get a little long, but I want to give the full background. Last november while on a hunting trip in the mountains (6000 feet elevation) my truck would puff blue smoke and run terribly rough for a few minutes when I would start it in the morning. After idling for a while or driving it, it would smooth out and run great. After 3 or 4 mornings of this the check engine light came on. Code was PO336. I replaced the crank sensor when I got home and its been fine ever since. Two weeks ago I returned to the same location as the hunting trip for a summer camping trip and as soon as I got there, the truck started doing the exact same thing again. Blue smoke and rough idle for a few minutes. CEL came on and code was PO336 again. The same time this started to happen, I noticed that I had a leaking power steering hose. The fluid was dripping down on the wires going to the crank sensor. The mechanic that scanned for the code thought that maybe the oil was getting to the sensor and messing it up. I haven't done anything to the truck since I have gotten home and it starts and runs fine now. I live in eastern South Dakota at around 2000 ft. elevation. Is it something to do with the elevation or is the mechanic right about the power steering fluid? I'll probably replace the crank sensor again just to be safe but is seems weird that it happens every time I go to that location/elevation.