I've had my stock air box off because of my intercooler. When I start the car up it idles up and down a little when warming up. When its warmed up it idles fine in park, but when I put it in to rev. or drive it sputters and feels like its doing to die out, but then comes back around. But it idles at around 650 in drive and rev compared to 800- 1000 in park or neutral.

I finally got my HKS RS intake and put it on and it still does the same thing. Any body know why?

Also, but I need to weld my BOV onto the intercooler piping now? It doesn't work ever since I put the I/C on it located in the stock postion right Now.
Please help me out.

 

As for the Idel first try reseting the ECU. Unplug the battey and press the braks for 30 sec. this should reset the ECU. If that dosent help then adjust it with the screw that is on the right side of the throttel body.