Del Sol 1.5L

• Automatic transmission
• 112,000 miles

I was planning on going to the beach today with a friend of mine when out of nowhere my transmission decided to downshift me out of overdrive and into neutral. I rolled it out into her driveway because, thankfully, I wasn't far from her driveway. I couldn't make it the whole way but I turned the car off and then back on and it drove out fine. When I turned the car off to go get her I went back and turned the car on. As I was reversing, I got about half way out into the road when the car shifted back into neutral by itself. We pushed it up back into the driveway and turned the car off, waited a few minutes, and tried again after about 10 minutes. We made it further into the road, but the same problem occurred. It won't shift out of neutral at all now. The stick will physically move to all the other gears and (obviously) has no problem going into park, but all the gears are acting as neutral. The car will rev up fine but no shifting takes place. I had a friend come over and do a quick analysis and he said I would need a tranny flush. We topped the transmission fluid off thinking that would be a temporary fix but the same problem keeps happening. I have no idea what to do short of a total transmission swap. Honestly, the car had problems idling due to the A/C, but I never thought this would happen because minus the idling problem, the car was spotless as far as problems went.