Trouble starting when hot

I have a 1994 Dodge Stealth with 168000mi it has a
6 cylinder engine I'm not quite sure what size. On the plate it says 6G72 .The following has been rebuilted heads,transmission,clutch.I have borrowed this car from a family member. Anyway it runs fine untill it gets hot and you turn it off .If its allowed to cool off a little it starts ok but try to start it immediately it has trouble.Sometimes give it alot of gas and it starts.Sometimes I must let it cool 15mins

Thanks for any Information