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Discussion Starter · #1 ·
2004 Sonata – 4 cyl. – Automatic – 95,000 miles

Sometimes the car runs beautifully. Other times is starts spark knocking, lurching, minimal response to accelerator positioning, occasionally stalls…almost like it is running out of gas. I have tried a gas additive to get rid of any potential water in the fuel tank, over the course of 3 tank fills…didn’t help. The fuel level doesn’t seem to have any impact on the problem. It flares up with ¼ tank and also with ¾ of a tank.

It will sometimes run great for a few days, then it will act-up for a day or so.

Any suggestions…
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