2002 WRX 4EAT Automatic Transmission - Noise and inconsistent engagement

Feedback, please.

2002 WRX w/an AT trans. 168K miles.  Car was purchased w/a supposedly non-working transmission. But it drove on the trailer and to the DMV, so I did the 3X drain/refill/repeat and the car seemed to drive - mostly - fine. And I just upgraded the turbo and the car drove fine while checking out the tune. This included full throttle accelerations @ 50+ and from a stop. The trans would shift down when the pedal was floored and accelerate normally*.

Except for these issues: 

1. There's a grinding noise that ONLY occurs when the car is moving AND accelerating. Doesn't occur when coasting or just stopped and idling. Sounds like it's under the driver's area...but could be the TC, too.

2. Occasional hard shift into Reverse and when downshifting from 4>>3rd>>2nd>>1st. Doesn't 'hold' the shift, just a more noticeable clunk into gear.

3. ONE time only today   - car had been sitting overnight- I pulled the car around to my garage for an oil change, and after hitting a decent size puddle/pothole (but no worse hitting a speed bump a bit fast) the car Stopped Accelerating. I shifted thru all gears and nothing. Put it into Park for 10 seconds, tried D once more and the car started moving and drove into the garage w/out further issue. I checked the fluid, which looked/smelled OK and the level was good. After doing the oil change I took the car for a 'spirited' drive on the freeway and local winding road and it worked fine.

- No CEL / Transmission codes.

- Transmission has BEEN REPLACED already (it has a Reman. sticker on it), but I don't know when/why or @ what mileage. Doesn't show up on the Carfax and my Subaru parts dealer didn't see that it'd been replaced by a Subie dealer.

So, I don't know what to think. Other than I've probably got a transmission project in my future.

Thanks,

TD

* The Subaru 4EAT on a turbocharged model just plain sux for off the line acceleration. My Forester XT was equally unresponsive.