89 F150 hard to start after driving for a while.?

300 in line 6 cyl. New top of the line battery, starts great when cold and after short trips. But after driving for 45 mins or more if I run into the store for a few minutes then come back out while it is still hot it lurches a couple times before starting. Any ideas? Starter is about 2 years old - a rebuilt from AutoZone. Otherwise engine runs great.