My low mileage, completely stock 1994 Mustang Cobra (#500 of 5009) squeals / whines for a few seconds after I turn the engine off. The squeal / whine comes from under the hood and seems to be related to the fuel pump continuing to run to build pressure after engine is turned off. The squeal / whine will also occasionally occur at idle but a light tap on the throttle makes the squeal / whine go away temporarily, but as soon as the engine returns to idle it comes back. Seems to me to be related to fuel pressure so I replaced the factory fuel pressure regulator with the expensive Bosch fuel pressure regulator but the squeal / whine persists. What is that little round chrome disk/part on the return line? Flow control? The whine seems to be coming from there, but this is an irreplaceable part and only included with the factory fuel lines which are only available used.