At times when turning on the hot water faucet we only get a small amount of water. We then turn it off and then back on or even turn it to all cold and then all hot, it finally returns to full pressure. This is not a one faucet problem so I am inclined to think it has something to do with the hot water heater. Any suggestions?

What type of water lines is your home equipped with and what is the approximate age of the Home. If your home is equipped with Galvanized water lines this is more than likely your cause. A lot of homes have had only on side hot or cold updated with plastic or copper and would explain why it is only on the hot.

I agree with Locken,
My place is piped in galvanized and I just repiped in plastic.

We then turn it off and then back on or even turn it to all cold and then all hot, it finally returns to full pressure. Do you have full pressure after that or does it fall off after a few minutes? I don't believe it's the heater by itself. You have something else going. Regards, Tom