Intermittent Stalling (97 Taurus)

Hi. I'm trying to figure out what's wrong with my 1997 ford taurus (automatic) with ~57,000 miles on it.
It intermittently stalls/idles out when coming to a stop, when driving
normally, when going around curves, when putting it in reverse or drive, and sometimes even when I just turn the car on. When it does it driving normally, it just seems to lose acceleration and I can mash the pedal to the floor. The rpms go up slightly, and sometimes I can hold the pedal down or keep pressing on it and it will kick back in, but I usually have to slow down and it just idles out, and I have to restart it. I have noticed, though, that if it's doing this, I can switch it into 1st (gear?) position and it will kick itself back in. Does this sound like a tranny problem?
I have gotten the throttle body cleaned, the throttle position sensor replaced, the idle air control valve replaced, fuel filter replaced, and the spark plugs & spark plug wires replaced. Still, the problem persists.
I have called around to multiple technicians and one said it could be the fuel pressure regulator or the EGR valve/sensor or the EGR intake manifold needs to be cleaned. Another technician said it could be the torque converter locking up. The service engine light only comes on when it stalls out, but it goes away when I start the car back up. I have had it tested at autozone with their code reader and they could not find a code. It even stalled AT the autozone and the light came on, and I had it tested while it was still on. Their reader found nothing. Is it a problem with their reader, perhaps?
Also, I have never had the tranny serviced before. I was told it needed to be serviced at 35,000 miles. I did once have a problem with the transmission that seemed to go away on its own. It was leaking fluid and I would usually have to add a quart or two every now and then to keep the level up. Eventually, it just stopped leaking. I figured this might count as a tranny flush, but I was told by a mechanic that I was wrong about that, and it still needed to be serviced.
I'm getting tired of throwing away money into the car and would like to see if anybody has any experience with this same problem or any opinions. Anything you could contribute to help me out would be appreciated greatly.
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