funny idle that aint so funny

[the Driver]

hello peeps , after spending 2 weeks with my bro fixing my new mk2 gti 8v , including rebuiling whole top half of engine and other various woes that the car had ,we got her reborn, it is finnaly up and running , only thing is when u start her up , and leave 2 idle the car sort of stutters.
It starts up sits at about 900 rpm but say every 3/4 seconds the car stutters and drops very quickly 2  about 600rpm then goes back up , if u put gas down it runs and sounds perfect, any ides plz ?,. 

 Now i know first hand how my driver likes 2 idle like a buffon , but i just built this and was hopeing if it started! that it would run super sweet. so any ideas are welcome .
it is a pb engine code if that helps

[elnigel]

clean the ISV, does it buzz, if not its knackered. clean intake, could be fuel filter, pump. or you could mess with the idle speed, theres a sticky at the top of this section about digifant running problems, its really good.

could also be the idle switch, which the throttle cable connects to at the throttle body.

probably the isv though

[the Driver]

thanx m8 ill have a look 

[Overseer]

you can also clean the ISV easily..

also check hoses for vacuum leaks

[Gambit]

reset the ECU

[Chris Green]

The Driver - is your car a K-Jet or Digi?

How do I reset the ecu? and is it safe?

Also, could someone point out where the ISV is on a K-Jet please?

Thank you!

[Gambit]

there is no ISV on an 8v k-jet