04 AWD reverse shutter

So picked up an 04' AWD 4.0 Mountaineer with 130k yesterday afternoon. Ran and drove great, especially on the 200 mile drive home. Got it home and decided to park it off my drive some in the yard. Upon trying to back it back up onto the drive, around a 3-4" curb it felt as if the tires were spinning and it wouldn't go. Finally it made it up and drove fine. Today went to do the same thing and it shuttered quite a bit and felt like spinning but tires were still. Now when backing up if you give it any gas over the slightest bit it jumps shutters and feels like possible binding. Any ideas of where to start? Like I said issue didn't start until I tried backing up the 3-4" curb onto drive.

Do you know when it last had a tune up? Maybe what you're feeling is a misfire that only occurs under heavy load. I'd kind of think at some point during the 200 mile drive you would have found some hill that would have triggered the misfire, but possibly not.

-Rod

I am unsure of when its last tune up was. I should have clarified that it only does this in reverse, forward and your fine. And it only does it in reverse if you give it a little more gas than normal, if you baby foot it it's fine. Does idle kind of rough with a shake, but smooths out as rpms come up.

It's a bit of a long shot, but since in reverse the gearing is fixed, it might be loading the engine just enough to induce a misfire that you don't really notice in forward gears. Since you do notice a bit of a rough idle, I would still recommend starting with new spark plugs and spark plug wires, checking and/or replacing the air filter, and cleaning the MAF sensor. Also, carefully inspect the vacuum hoses and fittings to see if any of them are cracked or loose.

-Rod

I will try those things first thing Wednesday! Hopefully that's what it is. Just find it weird that it didn't start happening until I attempted to back it up a curb. I've seen weirder things though! Thank-you for the replies!