Q: Why did my car rev in drive after stopping at a red light

So before i get into, i had a check engine light on the car for awhile, i thought it was because of the muffler, so i got all that fixed, the light went away for awhile so i went to get the echeck and passed. However, before i got my echeck the light would come on and off depending on how cold it was. but after the exhaust got fixed it stayed on, I havent had a chance to get it checked. I cant go to autozone to do it, because I need the real test done.

SO to the point, today this morning, the car started up normal as always, however, when i got to a red light and tried to go after the green, it didnt move, it revved like it was in neutral, i switched gears and it stayed doing the same. so i frantically turned the car off and back on, and tried again and it drove again normal, like why? im kinda scared to drive now cause its Saturday and no shops are open by the time i get out of work. Help?

My car has 131000 miles.
My car has an automatic transmission.