Craftsman 6.75 low idle

Hello. I have a craftsman push mower 6.75 hp model number 917.370411. The other day I went to start up my mower and the thing would barely idle if not stall out after a few seconds. I found that if I push the throttle on my carburetor to close the plate, it will rev up and run fine, so it seems whatever controls the throttle blade on my carb isn't doing it's job. There is a spring that pulls on the lever to close the plate, but even if I bend the bracket to the spring all the way back it's still not enough to overcome whatever is causing my idle problem. I don't know enough about carbs to know what needs adjusting or what is causing this problem. Any help would be appreciated.