Code P0302?

That engine has a few issues that can cause misfires. The biggest one is that it likes to drop rocker arms that cause misfires. While they are failing you can usually hear ticking until the arm finally drops out of the way. Do you hear any ticking or was there any prior to the misfire? The problem arises because of the roller bearing failing and locking up. That grinds the cam down and that creates the ticking, and the rocker falls off and now you get a misfire because the cylinder isn't filling fully. The only way to actually check is to pull the rocker cover off. You can also snake a bore camera into the cylinder and see if the valves are closing completely, there are times when the rocker will fail and create a burr on the stem that holds the valve off the seat. This is such a common failure that Dodge has a cam and rocker kit for the problem.

Sounds like the typical aftermath. You might try a compression test to see if that shows a loss. These engines are great when they are running right, they are a pain when they have issues. If you want a ton of info on them, you can go look at motorcity mechanics playlist David covers a lot of the issues and repairs on them.

https://www.youtube.com/playlist?list=PLM_FgFcXdM5r7IL3GoEoGLqGfFWT-en3A

It would depend a lot on what the problem actually is. If it's the typical cam issue it is repairable with replacement parts, shops do it daily. If you are not mechanically inclined with experience in internal engine repair, it isn't that fun. But it depends on the damage. It could be driven, but the issue then becomes that the misfires are likely dumping fuel into the converter and it's going to burn it out in time. If you are handy, you can remove the upper intake and the front bank valve cover. That would let you look at the valves and rockers. If the center of the cam isn't damaged and it's just a lifter off it is possible to pry one into place and run, it after an oil change. I think David covers that in one of his videos. If you could go that route, it would save a lot of time and money. I would do the testing first, you can get the tools as loaners normally. Then go watch his 3.6 videos and see if it's something you want to tackle.

The kit is available through most dealerships only. You tell them which cam(s) you need and the lifters for it. They stock a lot of the lifters. I'm not sire if there are aftermarket places that sell them any way other than singles.