23 hp v-twin Briggs only runs wide open.

i purchased a used husqvarna 2348. Mower looks great has 153 hours run time on it. Problem is when I start the motor it runs wide open. Can't figure out what is causing it, all linkages and springs look fine and appear to be working properly. I tried using a piece of stiff wire to hold the governor arm up all the way. No change in the run status, runs wide open, regardless which position the throttle is in. Any hints or suggestions, please advise.