i have a V6 and last weekend a buddy of mine with a 96 v6 camaro challenged me to race him just for fun (i beat him twice by the way) anyway ever since then, everytime i stop at a redlight or just leave the car idling it makes rythmic vibrations every 20 sceonds or so, now im worried i messed something up. Does any one know what this could be?

 

May be the exhaust system. The clearance for the dual system is very tight, and may now be making contact intermittently with the frame. My 73 Mach 1 CJ did this after we did some challenges to others before embarassing them. I put it on a rack and you could see the exhaust touch the frame, vibrate, then move away ever so slightly. Adjusted the mounts, no more vibration. Hope this helps.
Mach 73

 

That would make sense i will definatly take a look at that, Thank you very much!

 

Ya, take a look at the exhaust, however, Mach 73 mentioned dual system, which yours is not. Check the muffler hangers and make sure they are not coming in contact with the frame.