The AFM system is a faulty system that starved my lifters of oil and they ended up collapsing causing a flat spot on my cam. The engine code would come up as a misfire but the code is caused by the flat spot created on the cam by the lifter it’s a faulty system that cost me $7,000. My 8spd transmission also has a hard shift from 1st to 2nd pushing the vehicle forward and jerking it when it shifts. The dealer and GM said this was natural with this type of transmissions which we now know is a lie.