2009 G37x Automatic Coupe, 74k miles

I've done a lot of searching and found a lot of discussion on throttle lag and slow shifting but I don't think any of them really line up with my specific issue.

I know absolutely nothing about transmissions so my description will be terrible...
Sometimes when I'm off the throttle for a few seconds like at a stop sign or turning a corner then apply the gas the car will act like it is in neutral, rev, and take a few seconds to catch a gear. The harshest example I can think of is when I was at a stop sign that was uphill, moved my foot from the brake to the gas and gravity started rolling the car backwards like it was in neutral while it revved to a few thousand RPM before engaging a gear and moving forward like everything was fine. This type of thing has also happened turning corners, off the throttle -> turn the corner -> back on the throttle and the car acts like it's in neutral for a second in the same way.

I've had a short, rough history with this car.

1. I bought it "cheap" with a rebuilt title May 15th, it seemed fine. It looked like it would need some new brakes in the next year or so but nothing alarming. The idle would fluctuate a bit, down to the 500rpm marker at times so I cleaned the throttle bodies and it seemed solid after that.
2. I hit a deer a few weeks later, I think June 1st or so. It took a lot of body damage and my insurance company surprisingly valued the car way higher than I paid for it and covered it. I didn't get it back from the body shop until July 23rd.
3. When I picked it up from the shop I noticed a brake piston was stuck and drove it straight home and parked it until I got that fixed, I didn't notice the shifting issue but there were no stops. It is irrelevant but I replaced rear rotors, pads, and the back left caliper so far and the brakes are solid.
4. The next time I drove the car I noticed the transmission weirdness. I've only been driving it when I have to and have around 100 miles of small town / back country driving on it so far and nothing has really changed. I've learned to give it time to figure itself out so it isn't taking off at 3000+ rpm.

When the car was in the body shop I do know they had the battery disconnected a long time and when they reconnected it the drivers side window went haywire. The motor burnt itself out so they had to replace that, take it to an electric mechanic to get it fixed, and then charged me for it. Could my transmission problems be a computer/electrical issue? It feels like a problem that came out of nowhere when I got the car back from the body shop. It wasn't driven for seven weeks.

It's really hard to describe the problem, if anyone has any ideas please let me know. I did the ECU reset a few times with no noticeable results. I'm lost.

 

 

I don't see anything on here that should effect it, do you? I drove the car a few times after the insurance estimator came before I took it into the shop and didn't have these issues. I wish there was a reasonable way to check the fluid levels.

 

On second thought, I think I remember the autobody shop mentioning something about having to pull the radiator, probably the main piece in this image which was included in the estimate (62501-JK05A). The transmission part is in the same area isn't it? Is there a chance they had to disconnect it, reconnected it poorly, caused a leak and that is my problem?

Reading the symptoms of low ATF makes me think that has to be the cause, I wish there was an easy way to check it.

 

 

I just started having similar issue with my 2010 g37s sedan. while driving to work it was jerky when shifting and would get stuck in D it would not listen when I shifted to sport (manual mode) and would also not listen to the paddle shifters when I would try to manually shift the car.
I also noticed that it would not let me use the shift know to shift it manuall in sport mode. Had to pull over and turn the car off and open the door then restart to be able to restore it. it happened 3 times on a 20 minute commute
never given me any issues before.
and thoughts would be greatly appreciated. would low fluid be a cause? I haven't seen any leaks.