First thing in the Morning it starts normal with.

First thing in the morning it starts normal with no hesitation. Will not start when warm. After a trip, if I try to start it will have difficulty cranking then fire or barely crank slow. If it has set for 15 or 20 minutes it wil hesitate then crank and start. The longer it sets the easier it will start. I have had the battery tested at Autozone and checks good. The starter was replaced in 2006 with a new not rebuilt starter. I replaced it a few weeks ago for this problem since it was in warranty and did not help. It was suggested to clean the battery cables which I had done and it did not help. Any help appreciated. Thanks.