I just had this problem with mine, and it was a loose nut on the linkage. There is also a brackett held on by the transmission pan bolts, they were loose too. After tightening all these up it shifts fine again now.
footbrake deactivation switch
You did not have to apply the brake on a 91 model to shift it. There's nothing wrong.
Shift into neutral or park.
Inspect the shift cable that runs under the drivers floor mat. If the cable sheathing cracks moisture gets in and cause problems.
It is in the motor.
The cable between the shift lever and the transmission may be bad.
Align the shift indicator orreplace it. Your problem is strictly column mechanical.
Sounds like something is out of alignment in the transmission area. Make sure all the bolts are tight down there.
Shift Cable
you have to put your foot on the break pedal, to shift out of park its a safety feature
Does this happen all the time?
If it's an automatic transmission, it is attached to the transmission where the shift linkage is attached.