There is a common link. If you remove the black under-body trim that runs below the passenger door between the front and rear wheel wells you will find the accumulator (tank). Attached to the front end of it is a "valve" that supplies air to all four corners.

You'll need an 8mm, 10mm, and something to pry the plastic body fasteners apart to get in there. It's super easy, just be sure you make note of the two screws way up front. They are also holding the bottom of the front inner wheel well so they can be overlooked.

My advice on the topic which you can take or leave:
Opening up the bottom side should only be done to soap/water test for leaks. Do not disconnect or loosen anything. (I did and actually caused more problems).
You are likely to find one leaking airbag causing all of your problems but finding the leak can prove to be difficult.
Don't overlook the obvious - open the hood, remove the round, black covers on the strut towers and hit them with soapy water. See what happens. If no leak, spray down the bags themselves and also the fittings going into the bags. If still no leak, move to the back and try the rear bags. If you still haven't seen a bubble, open the trunk and flip the compressor out so you can squirt the fittings there. Lastly, remove the bottom cover and check under the passenger door.
By now, you've found your leak - if not, start over because it has to be there somewhere.

__________________
2005 4.8is