Had Similar problem Valves were checked and adjusted works fine now good luck..Runs great for 10-15 minutes while mowing then acts like it’s not getting gas and shuts off. It does start again but does off after about 1 minute after that. Fuel lines are clear and flows from gas tank well. Probably going to replace the carb this weekend. Hoping there’s not an issue with the coil as well? Appreciate any and all input in advance! New to the small engine game but ready to learn!