No reverse or drive 02 Explorer

[Poweha2]

I have a 02 Explorer with 196,000. I am the second owner and was told when I purchased the truck at 166,000 that the transmission was rebuilt at 155k. Recently I began having issues in extremely cold weather (below 10F) twice upon first starting out the truck acted as if I shifted into neutral after driving about 1000 feet. I shifted into N, then back to drive and everything was back to normal. Last week I was driving to work, the temp was about -10F, the truck felt like the automatic 4wd kicked in while doing about 70 mph. The Explorer started to slow, I got off at the next exit. Drive was gone, the OD light was flashing and "check transmission" was on the message center. Turned the truck off and back on, no idiot lights or messages. Was able to drive to work in 3rd gear. Since that the truck will creep backwards at about 4000 rpms and the same in D. It drives fine in 3rd gear or below. I have heard varying opinions from low trans fluid to the solenoid pack needs replaced to a rebuild on the tranny. Anyone had this experience before? I'm trying for the most inexpensive, long lasting fix that will get the Explorer back on the road. Thanks for your responses.