Q: Lack if power at 20mph

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Ok so when my vehice gets to about 20mph it will not accelerate any higher, also pulled codes po300,po304 and po306

Thought maybe cat.converter, but codes not for cat?

My car has 134000 miles.
My car has an automatic transmission.

Hello there. The P0300 series of OBD-II trouble codes indicate misfire problems. The 304 and 306 codes indicate a misfire on cylinder(s) 4 and (6). You might want read this article on the P-0300 OBD-II trouble code to review possible causes and solutions.

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