[sedanman]

Do you have some form of forced induction? If not 30# are way to much injector for your car. The change in fuel pressure is to be expected when you unplug the vacuum hose. Mustangs have boost/vaccum sensitive regulator so they change the fuel pressure depending on vaccum or the lack there of, the less vaccum the more fuel pressure its should be about 1 for 1. For every one inch of vaccum you should have 1 pound of fuel pressure pulled. I think a stock mustang pulls 14" of vaccum but I am not sure since its been years since working on a stock cammed mustang. So basically it seems you have to much injector but post your entire mod list.