I have a 2003 Ford Ranger 4.0L with 190k miles, the motor has always been very quiet. Upon startup the other day I had a screeching sqeal, which stopped after a few seconds. I was left with a flapping, clicking, almost exhaust leak sounding, sound in the upper starboard side of the intake manifold. The sound will go away for a instant when the throttle is opened, then comes back. The motor now pings at steady highway speeds. Power seams to be lower. I have checked all vacuum hoses, replaced the PCV valve & hose. The truck just had a tune within 5000 miles.