I'd like to post my scenario and some background, hopefully to toggle that one DIY'ers brain and get an idea of next steps.

I have a 2001 Grand Cherokee 4.0. My problem started about 1.5yrs ago when the car turned off at a stop sign. Started it back up, no problems and went on my merry way. The next several weeks this got more frequent. As the temps in Chicago dropped, I found it harder and harder to start my car in the mornings. It went from 3-6 cranks to get it started, to now 40+ cranks! And when the engine does start turning over, it rough-idles for a few seconds, then sputters and dies. I wait a minute, restart, it rough idles for a minute, then sputters. After a few attempts, the car will start up and remain on, but still rough idles. I'll shut it off, and back on a few times, and the rough-idling get's less and less rough. Eventually, the car starts to act and sound normal. Now the main rub here is the following: This is not an issue in the summer time, only the winter!

Here's what my buddy and I have done so far, in order:

1. Replaced Fuel Filter and regulator (one piece) from Napa

2. Replace spark plugs with Champion Double from Napa (with .035 gap)

3. Replace Coil pack/rail from Napa (at the time of spark plugs)

4. Replaced Camshaft Position Sensor and Synchronizer from Advanced Auto (followed instructions to get engine at Top-Dead-Center by handcranking and aligned synchronizer to appropriate position before installing)

These are the following codes I keep getting> P0320, P0352, P1391


So as you can see, I'm at a loss here. This shouldn't be rocket math, it's a Jeep for Christ sake. Anyone have these symptoms and tried the efforts I have, with a different path to try next? I'm also hearing Crankshaft Sensor or O2 Sensor? What I am missing here...

 

Crankshaft Sensor did the job. No more rough idles, misfires, and no more Check Engine light.