Aveo rpm/power issue

Hey guys,
I am posting this for my brother who owns a 09 Aveo with the DOHC 1.6L Ecotec. Everyone once in a while his rpm gauge will die and the car will have no power at all. None! Foot to the floor and it barely reaches 30mph. Next time he starts the car it will be fine until it decides to quit again. No engine light when this happens. He was reading and mentioned the crankshaft sensor. I looked for the location of it and couldn't find it. BTW>..it's not below the oil filter which was true for older aveo's. All I can think is that it's behind the timing cover. Any help or suggestions would be cool.