erratic idling

So I have a 76 KZ900 and I bought this bike not running, and all i have done to it since i have gotten it is clean the carbs to get it running, and adjusted them. Ran perfectly fine for about 2 months before i had gone down in my bike and had some what seemed to be just some cosmetic damage on one side. Im ok the bike was too or at least i thought. ever since then its been having a weird idle. i have to constantly adjust the idle with the "idle knob" underneath the gas tank. i would have to adjust it till it lowers the rpms so my bike doesnt burn itself out at 5-6 rpms. when im riding its ok but after every stop and even sometimes while im riding i have to adjust on the fly for proper throttle. i was told it needs maybe valve adjustments. appreciate the help

Check the carb holders for leaks.

Had a strap break and drop a bike in the back of a u-haul once, idled way high, couldnt get it to idle down

Checked for vacuum leaks and found none, ended up having to re-synch the carbs. Something got bent on me, i would start with checking for vacuum leaks with an UN-lit propane plumbers torch