I just bought a 93 ls 400 and I have noticed that at times when I step on the gas maybe to the floor to pass, the car revs but I dont really go anywhere, then it shifts pretty hard then I go. This doesnt happen all the time though. Sometimes I floor it and I take off like its suppose too. I just recently took it to the lexus dealer and he found that I have a cracked EGR pipe could this be my problem.

 

cracked egr is no problem really. that is just an exhaust leak.. could be bad TPS