i have a 2000 subaru outback with almost 200K miles on it has been great. out of the blue the ck engine light went on along with AT oil light flashing what could be the problem?

It could be a duty solenoid or pressure control sensor fault in the trans. Did it shift shock when changing gears? Like accelerating faster, dropping 4-3, shift shock, then drives fine until shifting hard again? You should have that code read. I generally refer people to try advance auto (and some other "mcparts" stores) for reading codes but it is always hit and miss on what their readers pick up. It is worth a try unless you have your own reader. Check out the code(s) and come back here and post it up.

I know you have an outback, but this is a good read, too. You can search if it applies to the outback. http://www.subaruforester.org/vbulletin/f89/temp-light-flashing-how-read-code-237225/

i change the transmission on my 2000 outback with a japanese transmission but is changing really hard and the at oil temp light is blinking like twice per second, what may be wrong and how to fix it?

the transmission it is supposed to have less than 50000 miles and outsider filter was replaced and new fluid replaced>