I just purchased a 94 GMC Sierra SLE ext cab. It has a electric brake, Firestone air bag in rear. I have no experience with these air bags. How much pressure to put in and how to maintain any help out there? The air valve are on rear bumper next to lic plate 2-valves
If you need them or simply like the ride feel , keep them.
If they are in poor condition (severely rusted, whatever) or you don't like what they do to the ride, remove them (as was already suggested).
I have bags on my 1995 S10 longbed and, with no load in the back and 10psi in the bags, the suspension is unnecessarily rough. I've kept them though; they do come in handy from time to time because it's my only true "pickup".