300zx transmission not engaging? Help!

[Jimjohn]

So I just bought a 1991 300zx 2+2 with 77,000 km on it drove it for a day all seemed fine than yesterday I was driving along in drive (it's a automatic) and I could feel she wasn't engaging the engine would rev and all just nothing engaging the wheels in any gear so I pulled over out it in park and shut it off and tried again nothing still a few more times I tried and than one time when i ired her over ans put it in gear she was fine like nothing happened for another few hundred feet than nothing again no noises and I have no warnin lights coming up on my dash anyone have any idea what could be wrong? any bit of advice will be much appreciated she gives out almost as soon as I hit the gas no matter how gentle I am

[nissanfreak12]

Rut ro raggy.......Autotragic strikes again.

How is the fluid? Level? That sounds a lot like it is slipping.

[Jimjohn]

Fluid is fine And so is the level she is making a humming noise when in park now that gets quiter when it is in drive