Yesterday when driving up hill on a highway at around 80km/h the Jeep started to jerk or buck. I gave it more throttle and the engine light started to flashed 2 or 3 times. When I reached level ground everything was back to normal. This is the 3rd time this has happened. First I noticed it back in the winter and now twice this summer on the same stretch of highway. I came home and pulled a P 0302 code by turning the ignition 3 times on/off. This is a misfire in cylinder two from what I read.

I have also read it could be anything from bad valves to transmission issues. I did install new plugs after the second time it happened this summer but it didn't help. What else can I do?

My Liberty is a 2005 LE and has 109000km on it.

 

You need new stock NGK copper core spark plugs!

 

Switch coil pack from another cylinder and see if the code moves as well.
I also use NGK copper core plugs and replace them every 25k miles.
Also to be on the safe side, have your battery load tested.