slowleak

I had the transmission (automatic) rebuilt in my 97 prelude about a year ago. Recently the car started intermittently downshifting and getting the flashing D4 light. The codes were P0700 & P0715. I had the input speed sensor replaced but I still get the code after driving the car about 20 minutes. Once I shut the car off and let it cool down the light goes away. I can drive the car short distances without issue but I really want to get this problem figured out. I've taken it to 2 different mechanics and they are both at a loss to as to why this is happening. Has anybody experienced anything like this?