since MP is a fish then he can have all PPs and AJ+ right. Discount AA and KK though but he may just call AK.

when he raises flop its 88,TT or AK right. if he has all AK hands in his range on flop then you are a 50.2% favourite lol. So just call flop and stack off turn i guess OR just fold if u think he 4bets AKo more often.