When I'm driving, the car will accelerate extremely slow at a particular gear with some noise underneath the car. The noise sounds like popping noise. The car also jerks alot at 2500rpm when when i accelerate. When i stop at a red light, the rpm needle is around 200rpms and after 10 seconds, it'll go back up to its normal 700 to 800 rpms. This problem occurs on and off. Any information would be appreciated.