2003 Roush Running slight rough, and really slow 1/4 times

2003 Roush Running slightly rough, and really slow 1/4 times

Hi
Ive got a 03 roush I bought a while back. I changed the sparkplugs, cleaned the throttle body, changed the tranny fluid, installed a steeda tri-ax, and put some nitto's on it. The spark plugs seem to make it run a little better, but still a slight shake every 3 or 4 seconds. I took it to the track and my fastest time was a 15.4, reaction time .013, 60ft 2.29, 1/8 mph 71.26, trapped at 90.29 at the finish line. I launched at maybe 1700 rpm on this run, previous runs were slightly slower and launched at idle, i shifteed at about 4700 1/2, 2/3 at about 5200, 3/4 4900 or so. I had 5 runs and this was the first time ive ever raced a car. My second fastest time i shifted at 5900, rpm or more every shift and let out of it before the 1/4 ended...i got scared lol

I checked the COP, the last spark plug had the rubber deal from the socket stuck on it, causing the coil not to be able to go down all the way I'm assuming. Its running a bit better now. Still has a very slight shake every 6 seconds or so. But not near as bad, I wasnt scared of the car, just scared that I might blow it up lol