engine reving high in park or neutral ???

[slideways]

Hi All
just got my lump back in the P38 and wired up but its reving high when in park or neutral i thought it might be the stepper motor but its clean as a whistle any ideas why this would happen?
Ta

[Trooper2]

Clean doesn't mean it isn't faulty.

Might also be a vacuum leak or the park/neutral switch on the transmission.