proberly is the tensioner, if your cam belt is too tight it will make it noiser, i slackened mine off a bit, now its fine,

If it runs fine with that plug disconnected its proberly a metering unit problem, or that fuel pressure actuator, its problerly cheaper to buy a second hand metering unit, than a new actuator from ford if available

if u had a valve stuck it would run rough with a good working metering unit