Transmission Problem Or Something Else? Help Diagnose, 2000 Galant

My 2000 Galant DE has been experiencing a rough shift for a couple weeks when shifting. It feels like it lurches forward (kinda like an abrupt shake/push forward), as I accelerate, about three times before it finally settles. I have noticed that it seems to do this at lower speeds around 30-40 mph when driving in town but not so much when accelerating at higher speeds (i.e. getting on the freeway). Also I looked at the color of the fluid and it is slightly brownish and the car noise gets louder when driving 50-60mph only and faster than that gets quieter again. It has an automatic transmission.

I started to notice this just a few days ago (hadn't felt this happening previously) and I have been thinking to see if I have done anything different to the car and the only thing is that when I took it to the car wash, they gave it an under blast, could that be the reason? OR...

The car has about 78,000 miles. I purchased it at about 2 weeks ago. Not sure if it had ever been flushed prior to me owning it. So I am wondering...

#1 if I should flush the ATF to see if it is just that the fluid has broken down and needs replacing.
#2 If I shouldn't flush it what else can I do to diagnose the issue?

Also, I have been trying to read as much info as I can find about this and it seems that some people have suggested it is not good to flush the ATF on some vehicles and that it depends on manufacturer recommendation, so does Mitsubishi recommend transmission flushes?

I would like to know what you guys think. Any other questions I can answer to help diagnose?

Thanks a lot guys!

You can flush it if you want, it PROBABLY uses SPIII. They have had problems with the O/D clutch causing shifting problems. It would be something to look into, there is a TSB about it.

My 2000 Galant DE has been experiencing a rough shift for a couple weeks when shifting.

I started to notice this just a few days ago (hadn't felt this happening previously) and I have been thinking to see if I have done anything different to the car and the only thing is that when I took it to the car wash, they gave it an under blast, could that be the reason?

Oddly enough, I've been experiencing the same issue after driving through some fairly deep water on the roads over the weekend.

I'm personally waiting to see if it continues to act up or if it clears its self up after some time to work out any moisture in the system.