Low water pressure in Excella

[murf]

Please help! My wife and I are having a problem with low water pressure in our recently renovated 31' 1995 Excella. We bought it from a salvage yard and spent 9 months re-habbing it. Everything is great except the water pressure is so low that taking a shower is almost imposible and filling the sink to do dishes takes forever! We are connected to city water via the appropriate hose and our trailer is the only one in the campsite that has this problem. The toilet seems OK but even the bathroom sink seems slow. The hot water is worse than the cold.

Under the kitchen counter top there is a black-plastic domed "filter(?) that has an air pressure valve on it that I don't know what it is or does. It is inline with the cold water line.

I've tried cleaning the inlet filter screen and even tried bypassing the regular inlet and feeding in throught the outside water spigot (as an experiment) and the water pressure is still low. What am I missing?

Thanks in advance for any help!

Murf