Trouble is on the horizon. Have a 99 baja outlaw sst with a 7.4 L 496 mag merc with an alpha 1 out drive. Bought two years ago with a new impeller at that time. Ran 170 last year. Have taken it out twice this year. Ran 175 on the first trip. Got up to 180 on the second. Cooled down at idle the first time. Not so quickly the second time. I did notice one riser is running hotter than the other. Anyone have any idea where to start?