Hello everyone. 04 CTS 3.6 84000 miles . a month ago daughter was driving the car on the highway when she said the car lost power like she took her foot of gas, she pulled off the road shut the car off and restarted, then the car was ok, this happed 2 times about 10 min apart. 2 days ago Wife got in car to come home from work , she said car reved up high several times CEL came on , the car bucked and surged all the way home. I started it when she got home and it was surging at idle. I rent a scaner and it gave me codes p2176, p0121, p0507. I was able to clear the codes , the car seems to be running ok for now . Any help would be great thanks.