Picked up an 01 tracker targa 18

[Tractionlesscoltgt]

Bought from an older gentleman that said he did all maintenance for the year and that the boat runs great. Long story short I hit that water last weekend and the boat will not go over 3k rpm. After looking around it seems it is in limp mode. Engine does not beep with key in the on position or while running which seems weird. The motor is a 2001 mercury 115 pro 4 stroke.
is there a diagnostic port on this motor? If so where is it located?
I want to start doing things but I dont really know where to start on a motor this big my last motor was only a 25 horse tiller handle 2 stroke on a v hull 12ft aluminum boat.
Is there a service manual for this engine?
any help/links are greatly appreciated.

 

[Tractionlesscoltgt]

Seems the engine is running extremely rich and has developed a misfire so I changed plugs took it back out. Ran without a misfire for about an hour still not exceeding 3100 rpms. Is there a coolant temp sensor on this engine if so what is the location and what ohms should I be looking for when testing with a voltometer?

 

[Tractionlesscoltgt]

Tested the thermostat in boiling water its opening and closing just fine. Any other ideas engine seems to be making oil maybe get a hotter thermostat?

 

[Tractionlesscoltgt]

Thermosensor? Would it have any direct effect?