Tranny Overheated?

I have a 1993 Acura Integra with an automatic transmission. I was driving a long distance the other day in hot weather, (Aprox. 100 degrees), and after about 45 miles into my trip the transmission started to slip as if it was low on tranny fluid. I exited off the freeway and found an auto parts store. When I pulled out the dip stick, a poof of smoke came out, like the tranny was hot, and it seemed a little low. So I put about 1 quart in, and it seemed to do the trick. But, when I got to my destination, it started acting up again. I put a little more in, and drove back home. I almost made it home before it started doing the same thing. I put a little more fluid in, and it got me home. Can the problem be that the tranny is overheating and when I put in new cool fluid it cools the tranny enough for it to run until it gets too hot? If so should I install a tranny oil cooler?