New SCT X3 91 and 93 octane tune

I am new to programming the computer on cars, although I've worked on computers for 10 years. I just bought a 2007 Shelby GT500 Cobra, which is stock. Since the car is set up for 91 octane and it's not available at many gas stations I bought a SCT X3 from a dealer and he made a custom tune for me for both 91 octane and 93 octane.

Today I picked up the X3 and installed the 91 octane tune and immediately noticed that the car idles around 1500 rpm when I stop and doesn't slow down to 850 rpm for about 6-10 seconds.

While driving if I let my foot off the gas it feels like I have the cruise control on because the idle is still at 1500 rpm.

When downshifting I don't get the same engine braking effect either.

Is this NORMAL and how it should be?

thanks so much in advance,

meterman

Thanks, acutally after letting the car sit for a few hours everything seems fine. Not sure if it's because I didn't shut the car off after installing the tune. Now the car runs GREAT. the boost kicks in as soon as I punch it, where it had a few second lag.