No water pressure on the hot side. - Price Pfister 532-7PCC Marielle Pull-Out Kitchen Faucet with Matching Soap...

mixing valve and ceramic washers are defective. American Standard is not what it used to be. Parts are substandard and imported from china. Get yourself a Glacier Bay, and contact American Standard and demand your money back or a credit.

If cold water has good pressure, and you are not on a well ,try turning water Off to water heater,open tap to relieve pressure remove hot side left water line to heater stick long screw driver inside pipe going inside water ,the heat trap is sticking it's rubber flap inside the pipe going in water heater.

Cold water pressure is what give you your hot water pressure so they should be equal but if you have a restriction on the hot side such as a valve not opening on the hot side or not opening all the way then you will have less pressure or the pipe work on the hot side is not proper. Hard to say but check the valve on top of the hot water heater

Could be. Location of the pipes has to start from the farthest part of the house to the place where the heater is at.

Just cap the open hot connection. When the valve is set to any intermediate position between hot and cold water will flow from the hot side to the cold side if there is any pressure difference. In your case the difference is your water pressure. You did nothing wrong you just did not finish the install.

Could be a chunk of scale in the valve. Need to turn off water supply and take valve apart. If nothing is found, turn water supply on to give line a 'quick' flush and turn back off. If this does not help, you probably have an obstruction somewhere in the hot supply line and a plumber may be needed unless you are handy. Good luck.

If you have full pressure on the cold water side and low pressure on the hot side then you well need to remove and clean or replace the cartridge for the hot side. If you have low water pressure on both sides try removing the aerator and cleaning it.
If you need to replace the cartridge on the hot side do both sides while you at it.
Whenever you work on any faucet before you turn the water on remove the aerator and run the water for a few seconds then replace the aerator.

We probably need more information to give a good answer.
You report 2 different problems occurring at once: Low pressure and Low temperature.
If this is tankless water heater, then Low pressure and Low temperature might be related, and you probably need a service technician to diagnose and repair cause.

If this is tank-type water heater, look at label on side of tank for type and brand of heater.
Is it gas or electric water heater? Troubleshooting is totally different for each.

Is water pressure pressure low on just the hot side faucet, or is cold side faucet affected too?
Are all hot faucets affected by low pressure?
If you have a dual handle faucet, open hot side only and check if hot water that comes out is hot as normal.
This will say if problem is pressure or temperature.
Tank-type water heater usually won't have both these problems occur at one time, but water heaters work in funny ways sometimes.

Add a comment to this post, or re-post your question with details so the experts can give a solid answer and not guess.
Also you can post water heater questions on pro water heater forum:
http://www.thetankatwaterheaterrescue.com/forums/forum3/

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

You have a clog in the hot water line.
If problem is at one faucet, then remove aerator and clean, then disassemble lines underneath sink.

If problem is at every faucet, then that moves search close to water heater.
Look at hot water line that exits water heater and trace that line to first Tee.
Look at cold water line that enters water heater and trace that line to Tee.
Clog is located between those 2 Tees.

Buy pressure tester that connects to hose thread.

Connect pressure gauge to hot water heater drain valve.
Then conduct same test you did at faucet.
See if pressure drops at tank.

If pressure drops, then clog is on cold side of tank, and probably hot side too.
If pressure does not drop, then clog is on hot side of tank.

Suspect 1 is any place two different metals join. For example galvanized pipe and copper.
Suspect 2 is supply pipes that exit top of tank. Take apart and look inside pipes for corrosion and sediment lining pipe walls.
Suspect 3 is elbow. Disassemble pipes and look for sediment and flakes of rust.
Suspect 4 is all suspects above, each having sediment and corrosion.

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

It could be back flowing into the hot water heater tank which is not full because of the leak. Even though the valve is closed on the cold water entry side, there is probably no valve on the exit side. That is how it is returning to the tank.