I have a 99 mustang gt and the check engine light came on about 2 weeks ago. I went by autozone and the the code fault was p0340. I bought and replaced the camshaft position sensor as indicated. Since then on start up the car backfires and has trouble starting on the first turn of the key. I can turn off the key and try to restart and it starts fine. I have checked all wire connections, and made sure the sensor was tightly in place. Does anyone have any ideas what I should look at next?