I have a Jeep Liberty 2010 had a few minor issues in previous years..Squeaking inside, they added form to quiet the noise, well it's back and my warranties out. Fast forward 2013, my engine light comes on one day after I fill my tank I think it's bad gas. I added an additive to clean the line, light still on. Then the jerking and sputting; the engine light starts flashing and the vehicle nearly stops on the expressway. I have a couple of codes (p0151, P2099) Catalyst Fuel Trim System Too Rich & Circuit Low Voltage. I finally get it to a mechanic and they say."Its an O2 sensor". I say although I only have 43,000 miles the bad gas maybe the issue and that it may need a tuneup. He calls back later and says a Map Sensor and now it's as tuneup. Although the plugs he pulled were strange. The right side had factory plugs(100K) and the left side, the side that was burning has different plugs (30,000 miles), I don't know how they got there? Is this normal for Jeep to do this? The problem is still not resolved and my vehicle is still at the shop and it's been a week.