Ok all one level bathrooms work fine pressure and heat, kitchen sink low hot water pressure and warm water not hot... ideas?

In replacing your heater you must have dislodged some minerals built up on the pipe walls and now it's clogging the cartridge. The solution would be to shut the water off. Open up the faucet and remove the cartridge. Check the inlet ports for any blockage and clean them. Now place a pan over the open valve body and turn the water on for a minute to flush out the supplies and valve body. Since you don't complain about the cold water I assume the aerator screens are clear. Reassemble and test. Better now? If not click back with the brand name and model number. Good luck, Tom

Us craft master e3f50hd045c

Why did you give me information on your water heater?

all one level bathrooms work fine pressure and heat, This tells me the problem isn't with the heater. You complained about the kitchen faucet and that's what I addressed. Have I missed something? Back to you, Tom

Some rust could be in the line and that could b the reason why it is not getting hot but it could be a lot of things that is just on off hand

Frogger, Tom and the rest of us are think it is your faucets mxing valve or cartridge si tell us about that. Then we can tell you how to clean out the debris