Car runs the same

Ok guys. Anyone every had a racecar that ran the same number with in a a couple of hundredths everytime ? I know what a problem to have right ! Buddy of mine is trying to make his car run 5.70s. He wants to run the 5.80 index race. The car run tonight at XRP raceway in Ferris Texas 75% humidity and approx 80 degree air. It 5.97 at 114. Last week he ran 5.99 with good air and 40%. He tried leaving at a diff rpm. Shifting diff rpm. Diff tire press. He even put the car on alcohol . the car ran 5.98 114. No matter what we do to this car it doesn't speed up or slow down. The car is 68 Camaro with a 532 with a 1050 dom. 488 gear. The car runs very well. He bought the just as I have described it. He has not changed anything but trying the alcohol. The only reason he tried the alcohol was it picked his other car up 4 10ths. 7.20 to 6.80s. Just was thinking out loud. Maybe one of you could think of something. Jets,timing,plugs,ignition all the usually things have already been done. And all was spot on.