I know the 91 year turned the throttle body, sensors, throttle and Tranny linkage 180 degrees around on the intake manifold. 97 made further changes on the TPS as I recall. The IAC and TPS on the throttle body changed in 91 as I recall. That's all I know, there is probably more that is different.
Why do you want to put the 97 parts on an 87?