I had a supply come loose from a kitchen two stem. After reattaching the supply the hot pressure was not existent in the faucet. I removed the aerator and the stem and cleaned debris out and the pressure was better, but not good. The supply came loosed again and I have replaced it - I think that is fixed, but now the pressure is bad and both hot and cold. I cleaned the aerator again and removed both stems and cleaned debris out of both sides. The pressure is now BAD in both sides still. Could there be debris in the center where the water mixes and comes out the "spout"? If so, how do you clean stuff out of there? I cannot figure out how to open that bit.

Shut off angle valves and remove supply lines from valve.

With a pot under valve and a cup to divert water, turn water on and see if you have full pressure.

If yes blockage is between the start of supply line and faucet.
With valve off remove faucet valve stem and slowly turn water on to clear line.

If no, blockage is at angle valve.
Shut water to house off and remove angle valve stem. With pan to catch water turn on house water for a few seconds.

This should clear your lines.

Let us know how you make out.

Chuck