The tailgate an my 1989 944 2.7 Lux seems to have developed a mind of its own- I've checked all the mechanisms, WD40-d all the electrics, degreased all the moving parts,and I can even see the catches moving when the motor turns, but even so I have only a 50% chance of the thing opening and shutting when I tell it to. Anyone got any ideas?

 

Are you confident that the latch and catches are correctly aligned to each other? Are the hinges worn or stiff etc? These could contribute to the closing and opening variation.
Regards Big Bob