Transmission on its last legs?

First problem with my 07 Ram here, and it looks like its gonna be a big one. Pulled outta my driveway today (which is a heavy incline) to take her into the back yard to wash her. It seemed to have a very slight hesitation at low rpm, like it wasn't sure if it wanted to go or not. Anyways, got into the back yard, and washed/detailed her. Upon pulling out of my back yard (which is also a heavy incline) it wouldn't go anywhere, and started acting like it was spinning out, and bucking a little bit, even though I could clearly hear the tires weren't spinning. The check engine light in the cluster also cut on at that time, not sure why. It stopped doing it after about 15 seconds, and I was able to pull out of my backyard.

Was pretty alarmed after that, so I took her for a test drive to see what was up. Took off fine, no hesitation, but once I got about 1/2mi down the road and on another Inclined road it started doing it again, bucking and stuttering. Best way to describe it would be like driving over a heavy rumble strip at 60-70mph. Once I drove off the inclined road, it stopped again and drove/shifted normal. Drove for about 20 miles after that, mix of highway and backroad driving, including a few steep roads, and it was fine. I couldn't get it to do it again whatsoever.

I'm thinking the transmission is on its last legs at this point. Hoping some of you here have been through this before, and can let me know what the best course of action would be, and what exactly I can expect to happen from here with this transmission. This just started today, the truck has been fine since I bought it. I don't wanna replace the transmission if it can be fixed somehow, but I don't wanna end up with this one breaking down on me at a random time, and getting stranded somewhere either. This is my daily driver, and I need this truck for work everyday. UGH!

If you haven't I would check for some codes

Trans fluid level okay? Also check your codes to see if you lost the pump prime. Could be a bad flat filter. Those have been know to separate at the plastic/steel seam and suck air.

Did it do this problem only in drive, or reverse also?

I have heard that some owners have had this before and I was the parking brake linings breaking off the shoe causing intermittent problems. Just something to check along with the other suggestions.

Thanks guys, I will definitely try those suggestions. I ended up parking it, and driving my other truck until I figure this out. I've got an OBD2 code scanner that will hookup to my laptop on the way. Never bought or had need for one before, as I've always had old classic's prior to getting my Ram, and the SRT Challenger, that I have now. The check engine light is still on, so it should have codes for me to pull. I'll report back with the codes, after I get them. I hope this turns out to be something simple, as Reman 545RFE's run $2600, with a $800 core here.

This happened only in drive too btw, and only when going up an incline. After it warms up I cant get it to do it at all. It's still disconcerting.

Ive been driving the truck again the past few days, and strangely enough it has been fine. The only code I got was for Misfire on Cylinder 5. Not sure how exactly that could have caused the symptoms I saw that day, but I'm gonna go ahead and get all new coil packs and install them next week. Might as well change the plugs while I'm in there as well. I'll flush/change the fluid and filter in the 545RFE just to be safe. I need it to last me a little while longer. If it goes out down the road that'll be the excuse I use for a Cummins/Man Trans swap.