Crankshaft Position Sensor?
I just purchased a 2015 Jeep Patriot at the end of this past August. A few weeks (600 miles on the vehicle) after the purchase I went to start the vehicle and it stalled out. The check engine light came on. Eventually, after letting it sit a while it started up and ran fine. I brought it in to the dealer who stated it had a bad crankshaft position sensor which they replaced. I waited 13 days for them to get the part in and the symptoms seem to have resolved.
When I got the vehicle back I noticed that when the vehicle is in drive and at a stop (like I'm sitting at a stop light ect) after sitting about 10 seconds the engine surges. The tachometer will fluctuate about 200 rpm up and down. It also seems to have a rough idle which I did not notice prior to the repair. I brought it back to the dealer who said they couldn't replicate the problem. After it continued I brought it back and showed them, and they said they recognized the problem but couldn't locate the problem and the vehicle likely needed to "break in" since it was brand new.
I'm an automotive teacher and strongly suspect that perhaps it has a faulty crankshaft position sensor or perhaps something software related might be going on. Since going to the dealer results in only frustration and the vehicle sitting there weeks on end, I'm going to attempt a repair myself. I just wanted to reach out and see if anyone has experienced something similar or has any suggestions.