Whats it mean?

Last nite i was driving on the hwy and when i started going uphill and stepped on the accelerator the engine died. not totally, but it was as if something cut off the fuel to the engine and the transmission disengaged. i let my foot up on the gas and it kicked back in. i could drive up the hill but not fast, about 40. on surface streets it would do the same thing if i stepped hard on the accelerator. i thought i would take it in after work today but its not doing the same thing now. i took it to autozone and it had the P2646 code that made it seem like an oil issue. i checked the oil, and it was low somehow, but not much. i added half a quart. no oil has been leaking, and i havent seen oil smoke in the exhaust, and i dont know how an oil issue would cause what seemed like a fuel problem. any suggestions?