here is a picture of the idle control valve it is an easy test unplug it.
Steve is right I have learnt the difference on CIS injection it is all about air flow.
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)