I think you have somewhat addressed this before, but wanted to check more specifically...
I have a Kohler kitchen faucet with a separate sprayer. When the spray is used, it dramatically affects the water pressure in the faucet, both hot and cold. It causes the water to cut off completely from the faucet, even when the sprayer is not in use. I have to keep playing with the faucet to get the water to come back to normal pressure. The only way I can keep it working is to NEVER use the sprayer. Unfortunately, someone else did use it recently and now I'm having continuous problems with the pressure. This seems to be a chronic problem with this style of Kohler faucet since my cousin is having the same thing happen with hers.
The model is Fairfax Series, single handle faucet with side spray, Model #12173.
Is this a matter of replacing the diverter and if so, could you please explain how to do this?
Thanks.

It sounds like have problem with the cartridge, close both hot and cold angle valves under the sink, remove the cartridge, open the shut off valves for a second one at a time have a towel on the faucet to catch the water, clean and install the cartridge see if your problem is fixed if not, you would need new cartridge, open the link below, Thanks.

John

Kohler Plumbing