I thought the 323's have the ZF transmission? Guess it depends on build date...Solenoid fix is for the GM's.
But, if you do have the GM, I would say the solenoid being replaced and you still have the symptoms is not a good sign for me or for you.... I think options are new valve body/ cleaned valve body,,,
I think if after replacing my solenoid, if I still get the reverse failure, I am probably going to shift it, as they say on Wheeler Dealers, and get a different car.