Mechanic changed the o2 sensors and spark plugs before finding out that there isn't any power getting to the coil packs. He said that it is probably the ecm is fried and it needs to go to a gm dealer mechanic. I am hoping that it is possible to be something else before i pay that kind of money. checked over all the wiring and it is all still in good shape. everything is getting fuel i dont know what to do