Re: battery
assuming the battery is good and ALL the battery, solenoid, and starter connections are clean and tight it sounds like your starter motor has a problem, it's also possible the engine is overheating and when it cools a bit it'll turn over slowly, couple of questions, how does it start when it's cold, when it finally starts after 5 minutes does it seem to run okay, does the problem repeat itself every time the engine has been running, shut off and restarted at operating temperature?