I have a Mercruiser 260/v8 with thunderbolt ignition. It bogs at 2000rpm?

When in nuturel it runs fine at any RPM, on the water it bogs at 2000RPM to the point it almost sounds like it will shut down, It idles fine at 700-900rpm and up to 2000rpm's runs fine. This just happened over past few days. Seems to have happened after I washed down the bildge after the tilt trimp pump was replaced due to leak, not sure is this could have done anything, but. Someone told me to check the choke on carb?