Could this just be an issue where the spark plugs need to be replaced? I have had the car for two years and don't think that they have been changed.
My car has 90000 miles.
My car has an automatic transmission.
It sounds like you may have a couple of different issues going on here. At idle your car should be hovering around 750-800 RPM’s consistently. This is generally controlled by the idle air control valve which a valve that reads the air intake as it comes into the intake of your engine and relays this information to the ECM which then makes adjustments according to air, fuel, load, etc.
The problem with not being able to get the car to exceed 3,000 RPM’s may be related to a clogged catalytic converter. the catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this 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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