you might have to replace the transmission range switch, or have a short in the wiring. or maybe it's a goof, and nothing is permanently wrong.
remove the #6 fuse for 10 seconds, and replace. drive to 37mph in D and stop. shut the car off. start it up. do the same thing (drive to 37 and then stop) and see if the light comes back on and it does the rough shifting stuff.
if so, you probably need to replace the switch. lots of electrical tests needed, blah blah blah.
this is an abbreviated version of what the helms manual says.