Steve, you say this fixed your lumpy idle, did it also solve the high pitched squeal on switch off?
Yes it did, what that squeeling noise was , was the air being blown via the vent to air hole in the Pcv diaphram housing.
She's quiet as now
When it squeels , it sounds like you have a squeeky Fan belt or pulley noise.Clue is when you shut the engine off it still does it, so you know whether its a pressure noise rather then a mechanical wheel squeel if you follow
