I have a single lever Koehler Faucet (only a couple of years old) and hot water works fine throughout the house except for the kitchen... hot water pressure is very low (just trickles out) but the cold works find and hot water works fine everywhere else ?

Check to see if the hose is kinked under the sink.

Shut the water off under the cabinet and open \up the faucet. Check the hot water inlet poprt/seat for trash or blockage. Before you button up turn the hot water on for a minute. Did you get a strong stream? If not click on back. Good luck, Tom