1G Idle surge? help

[GiRtHyTaLonTsI]

i recently install a magnus intake manifold on my 91 talon tsi. im getting a really bad idle surge, i replace the IAC motor brand new from mitsu and im still having the same problem. i had a boost leak test done and there was no leaks to be found. the BISS screw is bottomed out and the car still runs might idle fine for a couple of mins but will start to surge. even while i am driving if i sink the clutch the rpms will shoot to about 3 grand and i gotta shut the car off and restart it. any help will be appreicated

 

[DSM90AWD]

Check that your throttle cables are adjusted correctly so that your throttle plate fully closes when no tension is applied to the gas pedal.

If the throttle plate is partially open the ECU will try and correct using the ISC, but if out of it's adjustment range, you will get idle surge