2000 S22 Throttle Issue!

[1SLEDHEAD]

Hey Gang!

I have a 2000 S22 and it has been a super boat. Runs like a top!
Lately I've been experiencing an issue with the throttle.
I read about the ECTS system and its capability of going into "limp mode", but that seems to be something different.
If you run the boat at just barely under half throttle, the boat will slow itself down, almost to an idle without me even moving the throttle at all. If you move the throttle just a touch more forward, it will speed way up, not to full throttle, but close. This issue has made it impossible to surf or pull a wake boarder as the boat will not maintain either of those speeds.
The motor seems to be running perfectly. No issues with idle or check engine lights from what I have noticed. Engine fires right up.  Could this be a throttle position sensor issue? I tried to search but was unsuccessful at locating anyone with a problem similar to mine. Would appreciate your thoughts/diagnosis!
Thank you! 

[Sammamish Skier]

That sounds like a feasible failure. I believe there is a debugging procedure for the TPS in the shop manual. You can download it from the maintenance section.

[Capt Rick]

Vise grips the return line going from engine to tank?

[1SLEDHEAD]

Thanks for the replies! I will look for that TPS procedure...

Capt Rick- You thinking I should pinch off the fuel return line?

[Sammamish Skier]

Capt Rick is thinking that this might be a fuel pressure regulator issue. If you clamp the return it removes the regulators from the equation.

[toyotafreak]

Step one, check for ghost turds on the mass airflow sensor!