when i start my car,my fuel pressure jumps right to 90 psi,and stays there. now while im driving, if i smash the gas the fuel pressure goes to 45 psi.when i shut the car off it will take about 20-30 minutes to drain down.i already dissconnected the return line at the rail to see if theres a restriction in the line but it still stays at 90 psi when running.hope this aint to confusing

 

seems to me your FPR is stuck... and if its really 90psi your going to toast your fuel pump shortly...

The reason for the drop to 45psi under WOT is the fuel pump can't supply enough fuel at WOT @ 90 PSI.

 

Yep, either the regulator is stuck shut or clogged, or you have a restriction in the line before the regulator.