it may be your diff that's off...

in 85 it should have a 2.88 giving you about 2800RPM at 60
if you are actually showing 3100 RPM at 55, then wow, yeah something is wrong. my bet is somebody wanted faster acceleration and pulled the diff out of a NA vehicle bumping your ratio to 3.46, or maybe just put in a 3.07 from a standard year turbo.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!