I've got a '97 XJ 4.0 that has a long start. checked battery and cables, cleaned up fuel pump grounds. within the past couple years i have replaced TPS, IAC valve, TB gasket, plugs, ignition cables, distributor cap and rotor, and checked fuel pressure, mostly in an attempt to smooth out a rough idle. now that the long start has started happening i am going back to the fuel pump. tested pressure today. primed pump, engine off. took 4 or 5 key turns to get it primed up to 45psi and it immediately dropped down to ~38psi when key was removed. over the next 4 or 5 minutes, it continued to fall to below 30psi. ran this test with the fuel line going straight to gauge, so i know im not bleeding through injectors. engine running, it is relatively steady between 45 and 50psi. pressure drops precipitously when key is off. this feels like a failing pump/check valve to me but im no expert. is this most likely my long start issue? could this also cause rough idle? just doing my due diligence here before i spend an afternoon dropping the tank. thanks in advance!