What RPM are you leaving at? I just got DRs on 18s and it took me 6 passes before I figured out what I was doing wrong! My car was bogging or I was letting off the clutch to fast, what worked on my last 2 passes was 5k rpms and a quick slip of the clutch, I ran 1.80 60ft but missed a gear and blew the run!!! Tried it agian and pulled 1.87... Lucky you have 3.91s so you may only need 4000-4500 to do this.
217/228 .565 cam, th400 swap with 3600 stall, headers, GPI tune, VR intake, Bo white TB.