Optimax 90hp bogging down

[pwarner1231]

Hi, new here. I bought a boat with a 2010ish Mercury 90hp Optimax. Took it out for a test run and it started but took a number of tries. Got on the open water and it ran good. Shut it down to try out the trolling motor and electric trolling motor (about an hour). Started it back up and it ran good until I backed out of it, then when I applied the throttle it tried to go then bogged down. Right to about 1000rpms. I had to throttle it back, let it idle then I could get a minute or so of full speed before it bogged down again. No overheating issues or anything else showing on gauges. HELP? Plugs?