Hello I have a 06 Grand with the 4.7 I just did head gaskets on both sides, we did not drive it before doing the head gaskets. It runs great 80% of the time but it mess up when starting it . The transmission goes to 3rd gear only, it has the traction control light on, it codes P1603 , P0988 , P0871 , P0846 , P0700 ,P0882 , but if it starts out good it stays good as long as you don"t cycle the ignition . One time I had to tap on the power control module by the battery to get the code reader to clear the codes and run good.
Any help will be appreciated .
Thank you