STX 38 running problems

[rosey65]

I have an stx 38 with a black deck and 13 H.P. engine. The issue I am having is after I start it. It starts great, but when It goes above half throttle, it starts to race like the engine wants to blow. I can move the throttle down and it will run like a new mower lower down. I can't figure it out. Someone said the butterfly valve and someone else said something else. Anyone have any ideas? Anything would be appreciated..Thanks!

 

[Ledgemere Farm]

sounds like the governor linkage to me. 1st thing Id check. Have to look at it to be sure.

 

[rosey65]

Still working on it. I haven't been able to get back to it for awhile. I will let you know what happens!