wierd problem with 1997 50 hp 4 stroke mariner

[djandy]

my 1997 50 hp 4 stroke mariner will start fine i get where i am am going with no problem i can stop and fish for 30 min or more and try to start it wont start till after 5 min of trying after i get it started it misses till i get past about 10 mile an hour then runs fine till i stop and fish for 30 min or more or till motor gets cool if i fish for just 5 to 25 min it starts fine so i took it to a mercury dealer they rebult the carbs it run better for a year and now its doing it again.somthing about when the engine gets to a certain temp is when it does it

 

[guyjg]

...mercury dealer they rebult the carbs it run better for a year and now its doing it again.

How often do you use the engine?
How old is the gas?
Do you put stabilizer in the fuel like Seafoam?
Is there dirt in the fuel tank(s)?