2006 Kia optima lx
Could be plenty of things. So I'll ask if the Check engine light is on first?
Yes and ivvle gave it a tune up a new egregious valve and one coil
Mine also did this. Does the car also have a faint surge while driving at a steady speed (usually highway)? If the answer is yes, check your catalytic converter. There are probably 3 of them on your vehicle. One is in front right as you open the hood, the second is right behind the engine and third is under the car right before the muffler. The quick test is to remove the oxygen sensor on the front one. If you do that and regain power you have the answer. Don't drive it without the sensor for long though because it gets hot quick and could melt wires or possibly the fan. Mine was the rear one that was clogged, both others were fine.
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