kawasaki Fr651v throttle issue

So yesterday the mower was running like a top than today on the first job it would not throttle up? its not a broken throttle cable because its moving the throttle on the carb as it should but it stays at low RPM like the throttle is all the way down.

i had to adjust the carb just to get through the job which sent the engine racing but when i engaged the blade it sounded as it should but when i put the mower under stress it would bog down

any ideas?