We have a volvo penta inboard that hubby is having problems with and anyones thoughts would be appreciated as he'd like to fix it rather than put it in the shop, :the boat looses power under load, reaches maximum revs etc when started out of the water but when in the water & under load it looses power and wont reach the top speeds it used to. Have checked and replaced all filters, have cleaned out diesel tanks & lines & added new diesel.....hes thinking it maybe the turbo?