need help PLEASE
 

I have a 1998 foreman 400 4x4. here is my problem, I will be riding and after 10 to 15 mins. it shut off. I wait 10 to 15 min and it will restart, start riding again and 10 t0 15 mins. of riding and it shut down again. I looked and cleaned out the tank, inspected the pet cock and carb, all looked good. I was told maybe the ecm/ecu. I need help don't know which way to go.
Thanks