My Mazda sometimes won't shift up or down, it just revs. If I take my foot off the gas it will find its gear. It has 79K on the motor/tranny, and the fluid is clean. Do these years have bad trannies ? It through a code once, but the code did not return after it was cleared.

Anyone have any ideas, or where to start ?

 

is it a standard or automatic? is the fluid the right color? cause even if its darker that could be a problem i don't remember what dark fluid means but all i remember is its bad lol