I just installed a new pressure tank and pressure switch. Everything is set properly (air pressure 2 lbs less than cut on, etc). My pump (jet, not a submersible) will come on, run up to the proper pressure point then shut off. I immediately lose 20 lbs of pressure and then the pump kicks on and off very rapidly. I have to actually shut the electric off to the pump to get this to stop. Any ideas on what could be wrong?

The reason that we started working on this to begin with is that occassionally this rapid on/off would start on it's own for no reason. However, before we started messing with changing things, I could simply run water and the rapid on/off would stop. Now it's never ending and if I want to use the water I have to go turn the pump on, wait for the pressure to get where it needs to be and shut the pump off.

Any ideas you have would be appreciated.