We recently purchased a 09 chevy hhr and within the first 150 miles we got a check engine light, took it to the dealer and was told the fuel was running lean. he reset the computer and told me to put fuel additive in the tank. i did so and the check engine light is still coming on and the engine is beginning to stall and lose power....what are we to do, car still has a factory warranty, but can't get help... *tr