We were running errands with no problem, went home to unload and head back out and the car started running really rough, lost all power. It idols rough, semms to be okay when I hit the gas while in park, as soon as I put it in reverse or drive it does not want to go, and is very jerky. No power. What coul dcause this all of a sudden? We also checked the oil, which was very low, even though we were still about 700 miles away from the next oil change, added 2 quarts to get it to the full line.