My 2012 Liberty developed the same problem. Get it warmed up to temp, stop for 10 minutes and when you try to start the engine it misfires, stumbles and dies. Try to start the engine a second time and it fires right up like nothing was wrong. No error codes pop and the check engine light stays off. In my case, once I was able to come up with the repeatable scenario, I was able to use the live data on Code Reader to discover the O2 sensors were acting like the engine was rich on the bad startup. With that info I took the Jeep to my local genius Mechanic. It took him 7 times of repeating the problem to zero in on the cause. During the first 6 times his diagnostic equipment was showing a rich condition on the bad startup. For the seventh try, after getting the engine ready to trigger the problem he pulled all the spark plugs, cranked the engine after 10 minutes and put a camera down each spark plug and discovered 3 injectors that were sticking such that gas was leaking into the cylinder instead of being sprayed. The fuel pump pressure was also on the low side so decided to replace it, along with the injectors.
Mischief managed
