Both Mitchel and Alldata says key on engine off pressure should be 30-45 psi.
As previously stated you may have an insufficient fuel flow problem.
A couple of tests you can do...
With your fuel pressure gauge hooked up, Find a flexible rubber portion of the fuel return line and briefly pinch it shut. Be gentle and don't damage the line. This will tell how much pressure your pump is capeable of putting out. It should be at least 60psi. If it doesn't increase much or not at all then your pump is weak.
If your fuel pressure gauge hose is long enough, duct tape the gauge to the lower corner of the windshield and drive it. The pressure should stay steady and not drop under wot. Make sure the gauge hose isn't against anything hot and doesn't get pinched shut when you shut the hood. Also make sure it's not raining so you don't have to use your wipers.
If you think it's running lean don't overlook the MAF. Try disconnecting it, if it runs better then it likely is bad.