Transmission?

Hello,

We bought the car listed above used in 2011 with 42,000 miles on it. It has been a great car and now has 172,000 miles on it. I've done a lot of work to it. All the usual things from wear and tear. The biggest and most involved thing I had to do so far was the timing chain. Did the water pump as well when I was in there. Also, new chain on the balance shafts and tensioner.

The last year or so I've had the dreaded overdrive bounce that these all have. Just learned to live with it, I guess. From my understanding it is caused by programming in the ECM. Anyways, not a huge deal and I kind of got used to it. I have never had any problems with this transmission, ever! The axle seals were weeping a little bit but not enough to leave any puddles of fluid. I replaced the axle seals about 2 weeks ago. I found it very odd that no fluid came out when I pulled the half shafts. The car has been taken care of with regular oil changes. The car has been very reliable.

This past weekend I was running errands and was driving about 20 mins and came to a traffic light and stopped. I accelerated and when the car shifted to 2nd gear it was a very hard shift like being hit in the back end. Did the same for 3rd and then very quick to get into overdrive. The car was bucking and acting like it was missing. Did this all the way home. Took the car back out about 30 mins later and it was fine until I came to the first stop and the same thing happened all over again. I stopped in a gas station and shut the car off for a few minutes then back on and car was fine again until first stop some 10 mins later. I drove home and let it sit overnight.

Next morning I put the car up on wheel stands on level ground and check trans fluid. Fluid did flow out of the check hole so fluid level is good. Checked engine mount and trans mounts. Top engine mount was bad and drivers' side trans mount questionable so I replaced both. The front trans mount and rear trans mount I changed about 2 years ago. Drove car and it is no longer shifting hard. Is this solved from replacing the mounts? As hard as it was shifting, I can't believe bad mounts would do that.

When we had about 80,000 miles on the car, I wanted to have the transmission service done but my garage said no don't do it just leave it. So that's just what I did. Now the car is at 172,000 and original trans fluid. With this mileage I'm concerned if there was debris that was caught in a solenoid or something or if I've got a transmission that is going bad. The behavior was out of the blue and I've never had any other warning signs from the transmission. I have no engine codes or CEL. Car was tuned up this past summer, so it isn't running bad or anything. I'm driving the car for 3 days now and it hasn't done it.

Should I change the trans fluid and filter at this mileage? I know a flush is out of the question. I need this car and getting another car is not an option right now for at least a couple of years yet. I have not had a scanner put on it because I have CEL but I've read there can still be codes in history. I even called the dealer where we got it and explained to them what happened. I was hoping they'd have a history on that transmission from previous owners with this transmission, but they were absolutely no help. Said they'd be very reluctant to even touch the fluid without me signing a waiver. I just don't want to believe it's the transmission. Like I said, never ever had an issue with it unless you consider the overdrive bounce an issue. What should I do next?