So I was driving home, made a turn, car goes out of gear no noise or grinding, just the reving of the engine as if I was in neutral. Pull over, get help. Top off trans fluid, idle it. Try it again...IT WORKS. Now let me get this puppy home. I go 2 blocks and it does it again. It seems like it will go into gear when I first start then goes out. A few minutes later I can get it into gear again and I will have 3 seconds to 4 minutes before RAAAHAHHAHHAHA. Reving as if im in neutral. IT does this when I am driving or if I let off the gas and try again. Any advise?

 

Automatic?
200K miles and never serviced the trans fluid?
When it neutral revs their is a whining sound coming from the transmission?

That thar be your sump pickup impacted with crud and the trans is starving of fluid.

Might be able to do a drain with some hydraulic cleaner to break up and remove the gunk from the sump, otherwise you will need to drop the trans, crack open the case and inspect.