1999 Honda Accord Rebuild, Replace, or Flush?

I have a 1999 Honda Accord with a Automatic transmission. I have not had any major problems and I have my oil changed on a regular basis. I recently relocated to MD this June and again, I have had no major issues with my car.
In January, I began having issues with my car driving in 4th gear (D4). When my car was left outside over night (in cold weather), the next morning it would go into reverse but when I shifted it to drive it would make a click noise, the light for D4 would not light up, the car would move but it would not go pass 10mph. After letting it sit running for like 10-15 min, the car would run fine. I was able to make my 30min commute to work with no problems and the car would work fine for the rest of the day. This problem would only occur on nights that got very cold. Now that it is warmer, I have no problems with the car not driving in D4 nor do I hear any clicking noise. It does however have very slight and discrete jerking when excelerating from a stopping point.
I was told that I could have the transmission flushed (but in doing research on that, I decided to hold off because it can cause more harm than good) or have it replaced/rebuilt.
So what should I do, have it replaced/rebuilt, flushed, ignore it, or have it diagnosed? I plan on getting a new car in 6-9 months so I dont want to pay $2300 if I can wait a few months.

Thanks!