Fastcat314

I just bought an 03 accord v6 auto from an auction and i pulled it out and drove it off the lot and about 1/4 mile later the engine reved amd the car wouldnt accelerate. I pulled over, shut the car off, restarted it, and it drove fine for a second but it started to slip or disengage (would be a better word for it) in every gear even reverse. I put a qtr or trans fluid in It and drove about 3miles with no problems then it started acting up again. I need to check fluid again but besides that what could it be? I had an engine light codes p1257 (might have been 1256) and p0506 but the light went off while driving but those codes have nothing to do with the trans