Here's the scoop:
2000 Acura 3.5RL
200K miles
Never had a single issue with the car EVER. Tranny never slips, car never overheats, nothing, no knocking, zero anything outside of maintenance upkeep.

Here's what happened:

Car was driving fine up until yesterday. The car was making a trip down to Phoenix (about a 4,000ft. change in elevation, and into desert). Car drove fine going down, but on the way back my wife was sitting in traffic in about 105 degree weather.

While sitting in traffic, the D4 light started blinking, but the car kept running and she was able to get off the highway. Once parked, the car would not come out of Park unless she used to key to unlock the tranny. Once the car was in neutral it would start and drive a ways before sputtering and dying out.

It finally got to the point where the car was struggling just to stay on and the battery was draining.

I got it towed home, and here we are. The D4 blink can be a sign of transmission problems, but we have never had a hard shift, a slip, nothing with the car so I don't think that's it.
I've read the VSS can create issues SIMILAR to this, but I'm not sure on that either.

Main Relay? Alternator maybe? Would an alternator going out cause odd electrical things like the dash lights flickering, car sputtering, and transmission engagement issues?

Any help would be greatly appreciated.

 

Well, a few days and no replies. So I made a video showing what I mean. Now the car runs fine (motor-wise) with the jumper cables connected. The car will stay on, all lights work, motor revs freely without any hesitation or lack of power.....nothing. No noises, tapping, nothing from the engine. Now when I disconnect the jumper cables, the following happens: