There is a noticeable gradual loss of engine power at any road conditions. Also car maximum speed is less than the original top speed.
Car Problem Diagnosis
When a car losses power gradually and the maximum speed is less than the maximum speed before the problem occurs, is an indication of a possible clogged catalytic converter. This device located on the exhaust system, the purpose of the catalytic converter is to purge unburned gasses, if this device is clogged the exhaust gas will not pass through the exhaust system out of the tail pipe, when the exhaust gas has a difficulties passing through the exhaust system it creates back pressure to the engine thus making the engine to loose power. Of, course when the engine looses power, the maximum speed also is affected.
Possible Cause of Engine Power Loss and Decrease of Top Speed
Clogged catalytic converter
All about car Recommendation
Bring your car to a reputable auto repair shop and ask the mechanic to check the exhaust system for a clogged catalytic converter to confirm that it is indeed the cause of the problem, also have the mechanic to check the air/fuel mixture because this can cause a catalytic converter to become clogged. Catalytic converter cannot be cleaned that is why when the problem is confirmed you will need a replacement part. You can buy a replacement parts on any auto parts store, or have it buy online here at Amazon replacement parts.