Keep going back to the dealer. This is an emissions issue and is covered under warrenty. If anyone else works on this you could void your warrenty for this issue. I know its frustrating but the dealer is the only way to go. Maybe you need a differnt technician to work on it or even a differnt dealership...
But if it were my car I would fill it up with chevron 91 and add two bottles of techron cleaner. At 1/2 a tank fill it up again run the remaining fuel to low and then hope it cleared up.
If the injectors are spitting, BAD, instead of spraying ,GOOD. then you will have excess air from a misfire going over the 02 sensor. The computer will keep opening the injector ontime to maintain a 14.7 to 1 air fuel ratio. As soon as the injectors are at their max the car will buck like you running out of fuel.
This is about the only thing you can do at home.
You could try replacing the fuel pump relay and the ASD relay if you have them under the hood in the fuse box. There only about 15 to 20 bucks for the 2.
If you can feel the misfire and you see it happening on a scanner then look at the injector ontime. . This will give you an indication of the injectors being opened which would point to a fuel issue or vacuum leak
A vacuum leak could be the plenum gaskets are leaking

It was really cold for about a week her like minus 40 degrees celcius i started my truck its a 2008 dodge nitro and immediatley it started sputtering and there was this ticking noise coming from on top the engine i thought maybe it needed gas line antifreeze or injector cleaner so i applied it to the tank and the lines off the pcv valve and let it run .it still hasn't changed .i'm thinking about changing the plugs first then if that doesn't work the injectors