Q: My car wont get up pst 25-30 mph

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To start with the car belongs to my girlfriend. Its a 2002 pontiac grand prix. I never noticed a decrease in cars power output until she warned me. To me it sounds like the car may be clogged up so I was thinking possible catalytic converter, 02 sensor, or mass air flow. Could it be? I know her uncle had the car previously and he was the 2nd owner and drove the car everywhere.
My car has an automatic transmission.

Hi There, You are correct in that one of the main causes for a car to struggle to get up to speed is a clogged or failing catalytic converter. When the catalytic converter is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly. When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your catalytic converter.

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