87' F-150 psi?

32-37psi with vacuum line connected. It will go higher or lower depending on vacuum which can be influenced by a number of things. Having good fuel pressure at idle is no promise that it is good as the engine speed and load are increased. The fuel pressure is not adjustable with the factory regulator. You need a fuel pressure tested with the capability to run a delivery volume test with the engine running to know whether the pump and filter are acceptable.