I have a 502 built to a 509 pmefi did my ecm. The issue I am having is it has a 143* t-stat in it The temp consistently runs at 150 cruising or wot when I come back down to idle the temp starts to creep to 160-165 then will come back down after 8-10 mins anyone else see this or is this normal?

Thanks everyone

Boat is a 271 formula fastech I also have a dwp drive.