My dad has a 2009 silverado z71 that has been in out of the dealer 8 times. Today's trip will make number 9. Some of main problems are power loss with no warning and smoking like a broken stove. The dealer has yet to replace the engine but has replaced the valves 3 times, heads twice, and kinds of misc. stuff. He has been looking into the lemon law but Chevrolet states that it's been a slightly different problem every time he brings it in. Just wondering if anyone else has experience with this problem/s.