Starter heat soak ????

My duster has been acting funny when starting up after it has been driven up to operating temp (180*) After shutting off and sitting for a couple of minutes it will either crank slowly or hardly crank at all. I'm thinking the starter needs replacing, it is 5 years old and surrounded by tti headers. Battery is brand new and alternator was rebuilt last year. Just want to confirm before I throw a starter at it . Thanks