A M G Automan Group

I purchased a 2004 chevrolet 1500 truck from Auto Exchange Team in Ventura, California on 1/20/2014 and the following occurred:I asked them for the smog certificate and they stated it would be mailed to me in about 2 weeks. I felt this was not right but I thought maybe it was true. I stated to the dealership I need to be sure the truck passed smog and they stated it did.Within about 6 hours of receiving the truck the Check Engine light came on. I took it back the next day 1/21/2014. They could not check computer because sensor was out and I was told to take it back on Friday 1/26/201. I took the truck in on Friday, 1/26/2014 and I was told knock sensor #2 was out. On Saturday afternoon, 1/27/2014, I picked up truck and was told they replaced knock sensor #1 and #2 and head gaskets. Within about 4 hours of receiving the truck, the Check Engine light came on again. I took the truck back late afternoon they still could not run the diagnostics on the truck because the truck computer was not working. The mechanic took to the truck to a different shop and the different shop mechanic stated to give the engine 2 weeks for the computer to recognize nock sensors that were replaced. The other shop mechanic also stated that if the check engine light still stays on within a few weeks it might be the vacuum.