i notice the same thing with my DSM from time to time. It seems like sometimes the clutch doesnt disengage all the way, but i expect problems from an 18 year old DSM..not a fairly new mustang. Ive been to a few tracks that have a sloped starting line, but usually not enough to make a huge difference unless someone is pissing around staging.

this is pretty much the only reason i havent gone to the track yet, when i rev it up at a light to try to launch when it turns green, i always end up inching forward ! ??

When my clutch/throwout went the car would pull forward when in 1st just like you were saying, a 4k rev would move the car a foot forward, and idle would make it pull a few inches, even when the clutch was all the way to the floor. After a new clutch/throwout, no problems. -Jon