Why does my car sputter when I accelerate?
Sputtering under throttle is a misfire under load — the cylinder is firing fine at idle but failing when you ask it for power. The #1 cause is a weak ignition coil that can produce a small spark at idle but not enough to fire the rich mixture under acceleration. Next: bad spark plugs (especially if more than 80k miles), clogged fuel injector, or a vacuum leak that goes lean under throttle.
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