clogged fuel filter, or bad fuel pump
it could be the coil
Water in engine-head gasket most likely.
No. Bucking, I would consider an engine performance issue and shaking would be suspension or steering issues.
As you did not say which vehicle this can only be a general answer Unlikely that a faulty coil would cause an engine to knock. Very possible it would cause bucking, if the coil is failing there would be a lack of spark. This would cause bucking/missfire, which may cause the engine to shake on it's mountings possibly causing a knock from contact with the vehicle frame.
when my dodge stratus started to do that it was because I needed transmission fluid.
a long term cause
I sometimes sputter when I'm nervous. Please reword the question and tell me what year and engine and describe what you are doing with the car when "sputtering" occurs. Would help if you can think of additional description of what you mean by "sputtering".
If the whole car feels like its bucking it could be the transmission is slipping. Either its going bad or you need to get new transmission fluid. Sometimes older cars, especially automatics, do that if you put in a lower gear other than drive.
Its your coil packs, they become defective after time, it causes a sputtering and loss of compression. Also check the intkae manifold. the throttle body control will regulate fuel to stop sputtering set idle for around 900rpms
The fuel pump will cause it. Check the fuel pressure. It should be between 55-70.
One cause would be a cold spark which means you have either a loose coil wire or a bad coil.
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