Engine Performance problem
2003 Chevy Malibu 6 cyl Two Wheel Drive Automatic 61000 miles
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With my 2003 Chevy Malibu, I notied a couple of months ago driving at highway speeds that the engine gives off a low, constant humming sound. I know it is not the tires as they are new and were on the car prior to this issue. I also feel a loss of horsepower, especially when trying to accelerate or pass. I can get the engine to kick in if I give it a lot of gas, but it used to accelerate much smoother and faster before.
The engine starts fine, but does idle a little louder than it used to. Sometimes, mostly at city driving speeds I can feel slight hesitation in the engine.
What could possibly be the problem here? Could it be a fuel system issue? I am mostly concerned why the engine emits that low, constant humming sound at highway speeds, normally when I get up to 60 mph and beyond. Thank you.