1997 Evinrude Intruder 150 Running hot on Starboard Side

My Evinrude Intruder 150 (E150ELEUE) runs hot on the starboard side after running WOT for a breif period. The motor stays between 140-155 F at idle on both cylinder banks, but after running for about 5 min at 4000rpm the starboard cylinder bank measures 197-203 F and the port bank is 156-160. When this occurred I removed the starboard thermostat and it was open, and it closed when I dunked it into the river water. I replaced the water pump within the last month. The water pressure at idle is about 10psi at idle and 35-40psi at 4000rpm.

Does the hot alarm sound????

if I run it long enough the temp light will come on and it goes into SLOW mode but I don't remember hearing the alarm. The last time I ran it I just monitored the temp with a heat gun rather than pushing it until the alarm went off because I didn't want to risk messing it up but I wanted to be sure it was actually overheating.

Replace the t-stat/poppet assy and make sure the sleeve is in place...

I replaced the t-stats a few years back with what the other style of thermostat that are incased in a white plastic housing that doesn't work with the sleeves like the originals. I just assumed that it was an updated version and it seemed to work fine. I'll haft-a try to find the sleeves, marine engine dosent have them.