Tohatsu 18 HP wont run at full throttle.

Just got a used pontoon boat with a 2008 Tohatsu 18HP engine. It had sat for over a year in shrink wrap but was serviced before I picked it up. They said it had a blocked jet but that they fixed it. Took it out on saturday and initially ran a little rough but eventually cleared up and ran fine the rest of the day. Ran it all day on sunday and was fine. ran just above 5000 RPM at full throttle. Spent the night on the boat then on monday it started up and idled fine but when tried to go to full throttle would only reach 3000. Everything else appears to run fine. Doesn't run rough or anything. Reaches 3000 at about 3/4 throttle but when pushed to full, will not go any higher. In reverse it will go to over 3000 rpm.

bring it back to the shop that serviced it and tell them its not running right

if that is not an option then I suspect its got a blockage in the carbrater again but just to be sure

check your compression on the motor, in reverse you have a lot less resistance on the prop so its going to able to reach higher rpms.

the motor being shrink wrapped just traps moisture and the motor may have serious internal corrosion issues because of it

you should only shrink wrap the prop to keep water and snow out

Assuming you have an MFS18B2EP. Model/serial is everything; year is irrelevant.
1. Is there any seaweed on the prop?
2. Is the prop hub good?
3. Is the fuel fresh?

Hi Drewnox, did you find any solution to your problem?
Yesterday i faced the same issue with my Tohatsu!
Many Thanks