I have a 2003 Ranger edge 3.0 flex fuel 183,000 miles. I have been having a misfire problem, only at idle, always cylinder 3. Replaced the fuel filter. Just replaced fuel pump assembly. With the old pump my fuel pressure was 49psi key on engine off, and running at idle it was 59psi with a shaky needle. With the new pump, when I turn the key on it jumps to 60psi then imedietly drops to 49psi. Running it is at 60psi with steady needle. Koeo the pressure holds good at 49psi but does slowy decrease, about 5psi in 15 minutes. What would be causing the pressure to drop to 49psi? I am checking pressure at the fuel rail. Pressure according to the haynes manual should be 60-65psi koeo and the same while running at idle.

 

sounds like a stuck injector to me,, it stays open just enough to let pressure bleed down slowly, try some injector cleaner before replacing.