The fuel pressure will naturally drop after time. The trick is to keep the pressure up until the engine heat drops.
The pressure should NOT drop rapidly at ‘shut-down’.
There are several places for the fuel to leak.
Back through the fuel pump(s). (faulty check valve(s).
Faulty Fuel Pressure Regulator.
Faulty (dribbly) injector(s).
External fuel leak.
If the fuel pump(s) in the tank leak, I would install a check valve in the hose IN THE TANK past the pump(s), before the steel connector at the tank outlet.
You can try to find another spot along the fuel line but you will need to cut a factory line somewhere. If you cut a steel line, make sure you put a ‘barb’ or a ‘bulge’ so the rubber line will not become disconnected with fuel pressure.
Good quality hose clamps will help.