Problem with hot water pressure

[Namakemono]

I am new to Airstreams. I have a '78 25' Trade Wind. The hot water pressure has a small surge and then falls of to almost nothing. This is true at the rear sink, shower and kitchen sink. The cold water has plenty of pressure in the rear sink and shower and about half strength at the kitchen sink. I read PJUDE's post on his weak stream and saw his problem was similar but mine is primarily hot water. I do not know if I have the same inline filter he referred to. It is hard for me to understand what regulates the pressure out of the hot water tank. I would really appreciate some help from more experienced people.