45-70govt

So this is my first post and as the title says I would like to see if any of you have a good way to get rid of the emissions idle on my 2007 Rubi? I am not really sure what to call it, but it is how that the rpm stays up for a good second or two after the throttle is closed. From what little I can find it supposedly has to do with the fuel mixture and emissions which is why they have programmed the computer that way.

I just installed the Ripp supercharger kit and had hoped that the tuner would be able to get rid of it but no such luck. Is there any tune or "trick" I can use to make it idle down when the throttle closes like my good old 4.0 dose? At this point I would even spring for a new computer as this is very annoying!

Thanks in advance for any help. Been reading the forum for a while and love all the info here!!