Q&A

 Master

Backfiring under the hood is a sign of a lean condition, either a vacuum leak, air induction boot not secured to the intake manifold ect..., a fuel injector that is clogged and isn't supplying sufficient fuel, insufficient fuel delivery. A burned intake valve can also cause back firing. Back firing in the exhaust is raw fuel injected into the engine but not burned, it burns then in the hot exhaust. Jerking can be due to insufficient fuel delivery or failing ignition. To hard to guess or speculate without being able to drive the car first hand to get an impression of what is happening or being able to do some tests. Has the Service Engine Soon/Check Engine Light come on ? If so a scantool will certainly quickly narrow down the diagnostic troubleshooting time needed to figure out what is going on.