Help: 2009 assault after putting head on Dosent idle well. Any Ideas?

[o3polarissks]

I have a 2009 assault with boysen reeds an slp billet head and air horn intake. After putting the head on dosent idle well. with sled on the stand an giving it gas an letting off the rpms drop to 1,000 rpms, almost wanting to die.
Any ideas??

 

[milehighassassin]

Check your TPS (throttle position sensor).

It would a least be a good place to start.