Problems with my durango?

So we have a 2006 Dodge Durango 4x2 SLT with the 5.7L multi-displacment motor. It has this weird problem when it will be idling really rough and the truck starts vibrating. I tried driving it while it was idling roughly and it took atleast 10 seconds to get to 20mph and the vibrating got worse and didn't stop. So I turned off the truck and restarted it and it was fine. Ive noticed that the truck also starts vibrating when im going 85ish which shouldnt happen. I know it shouldnt happen because I took a trip to florida with a friend who also has an '06 4x2 just like mine but theres was fine and didnt shake going 85. I've taken it to the shop twice and each time they said it was the "o2 sensor". Its starting to vibrate again and I want to know if I should sell it, claim it as a lemon or just fix it and keep it.