Won't start when it's hot

Hi everyone I have a 1995 chevy lumina 3.1 it drives great but if I drive for a little while and turn it off it won't start back up right away you have to let it cool frist. Ii've had the starter, alternater, and battery tested they said there all good I ask someone else and they ask if I tested the starter while it was cold yes it was cold didn't know you could test them hot. Another thing it's always done is after driving for a while it starts to smell like it's (letting gas) yeah like a person but twice as bad. If anyone has any answers it would be helpful thank you!