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If this started directly after getting fuel then the first thing I would suspect is a fuel contamination issue. If the fuel was contaminated with water or anything else then will cause the engine to run poorly. If this started just after getting fuel then I would take a sample of the fuel and see what it looks like. Make sure it's not cloudy and doesn't separate after sitting, isn't brown, doesn't smell stale, doesn't leave an oily film on your hand after it evaporates, etc.
If the fuel doesn't seem to be contaminate then the next thing I would do is check fuel pressure under load. If the pump is failing and causing low fuel pressure then it may run ok at idle and lower engine loads but will hesitate and backfire under harder acceleration.