my car has no codes that are being thrown, however it goes really rich at 3300rpm and only made 199hp to the wheels last night. 8 months ago it made 252hp going off the scale rich. i think that there might be a false knock proble going on, but i only thought of that after i left the dyno. i aslo think it might have something to do with timing advance. please anyone in the dfw area , if you have a scan tool for an 1988 l98, please reply and maybe we can meet up! id like to get the problem fixed before i put the ls1 in.

Do you have or have access to a laptop? If so, just download TunerPro, get a cable, and data log it yourself. Then there's lots of folks on here that can help you "read" those logs. But be prepared to get into chip burning if you want to make any changes to speak of.....

As far as a false knock goes - check your exhaust/header bolts. Mine loosen up about once a month and start wreaking havoc with my soark advance. Just tightened them up over the weekend (again)....