1996 Honda Accord loud noise and difficulty accelerating

1996 Honda Accord Ex mileage: 120,000. My car has some difficulty in accelerating when I stop at a traffic light and then proceed. It will not go beyond 20 mph, and the engine has a loud noise. Thirty seconds later the problem disappears. The problem occurs occasionally, especially on local roads. In addition, I was told that I need a valve adjustment very badly when I did the oil change this January. Does the problem have anything to do with it? My transmission is leaking.