1993 Honda Accord starting car

Last year, when hot weather arrived, I started having trouble with my car starting when the weather was very hot. It would crank up just fine every morning, and after work every afternoon, it would not start. It would turn over very well, but would not start up. I would hold the gas down and keep trying until it would finally start. Hot weather left, and I have not had trouble with it until this past Thur. It got up to 83 degrees outside, and I went to leave work, and it would not start. It turned over very well. But took me a long time to finally get it started. I took it to a mechanic, he put a new distributer on. Today I left @ 2:30 in the afternoon, and it would not start. So, same routine. I went and made several stops, and never gave me anymore trouble. Please tell me what you think could be wrong? I don't understand why it only gives me trouble when it is hot outside.