its a 75 chevy vega backhalfed car with ford 9 in rear w/4.56 gears with ladder bars and coil overs. im running a 383 putting out 485hp and a glide. right now its aver. 1.52 60's and a best time of 10.92 @ 122mph in the 1/4. the car leaves straight but it doesnt stay consistant ... it will run from 10.92 up to 11.10's... im cant figure out why?