Well from excitement to pain - I rang the dealer for the Fuel Pressure Regulator price - £263 which is over $500
. The part numbers for different engines are different and this must be 16v specific.
I suppose I should determine for certain if this is the problem then. I've not seen any fuel leak out of the clear vacuum pipe since that one time - perhaps a one off?
The AFM boot (lower half of the AFM) is a more reasonable £30. I might take the AFM and distributor off to look for cracks in the rubber boot. Hopefully AFM and distributor can come off together. But i might separate them to see if the plunger moves freely. Does anyone know how to check test this or what to look out for?
Also I'm not sure if a cracked AFM boot would give a lumpy idle? Nor the fuel pressure regulator for that matter.