Drivetrain AOD is very intermittent

[87fbmustang]

Hello all! New here! Created this account to ask questions for a 1987 LX Mustang at my school thats been there for a decade due to transmission issues. Rare parts, lack of money, etc etc, we only just fixed it the other day. I am encountering an issue where the transmission only sometimes grabs drive, or only sometimes grabs reverse. It BARELY goes into park, and I am assuming it's a shifter issue. It has fresh fluid, the cable seems tight, any tips are greatly appreciated. It could be as simple as adjusting it, however I am not sure.

 

[General karthief]

Raise the rear tires off the ground, a lift would be nice, disconnect the shift linkage at the trans and start the car, move the shift lever on the trans park, drive-3 clicks, then apply brakes stopping the rear wheels, 2 clicks back should be reverse.
Do this at your own risk, always apply appropriate safety measures.