Hey guys just a little background of the car. Full bolt on boss mani auto with 3.73s. The boss manifold was installed for a year and a half and the lund tune was days after. Car ran flawlessly until around 1,000 miles ago. It drinks a ton of gas and is running really rich! It backfires on every single downshift and shoots a flame out occasionally. I read shauns thread a while back about the front o2s not being properly calibrated because the rears are off. Could they be bad?