MAB

My sr sounds like it is nocking even though i dont think it is. I was driving and playing with a talon turbo. I droped into low gear and proceeded to do about 18 pounds. After i left the talon behind i pulled into one of my friends neighborhood and ever since then any time the car idels it does it really like so low it feels like the motor is going to stall. It does this at about 3 or 4 hundred rpms where as before it ideled at about 6 or 7 hundred. All long with the low idel my boost gauge stoped working and when i let it idel now it sounds like it is nocking really bad. If anyone has any idea as to what the problem is let me know. I really need to fix this and would greatly appreciate anyones help with this problem.