RV water pressure in gal(qts?)/min

[bpaikman]

You mentioned that you fill a bucket quickly with the shower. If your shower has adequate volume it is obvious that your flow issue is not related to the pump. Many single handle pull out/down spray faucets will have a flow restrictor and/or check valve in the hose connection under the counter. Those can be carefully removed for better volume. Also fixed faucets will have flow restrictors at the aerator.

I totally agree. We can't figure it out because we had adequate flow everywhere on our long journey from Oregon... Except I recall some air getting in the lines. We were so busy adjusting other things that we didn't pay much attention.
We're going to tear into it after we deal with some other minor issues.