Hello all. I'm having an issue with my 04 revving to the point it sounds like it is hitting a limiter. I just recently replaced a bad thermostat and the speed control servo vacuum line which broke during that goat rodeo. Could the new issue be a result of the engine overheating? Lost for ideas here, hoping somebody could point me in the right direction.

 

Most likely a vacuum leak. Recheck that new line and others would be a good start.

 

I have checked all vacuum lines and they are good, but did notice that the throttle cable to the speed control servo moved freely. Could this be a problem?

 

That is normal (servo cable moving) -- it is meant to have some slack...

Think about all of the things you have disturbed in the process of getting to the t-stat and check them.