Yes, you could have a plugged catalytic converter
. They can also set EGR codes. The proper test is to use a back pressure gauge in the oxygen sensor
port. But, you can unbolt the exhaust at the rear manifold from under the car, ahead of the converter then see if power and acceleration is restored.
You could also have a faulty MAF sensor. You would need to look at airflow readings of MAF to see if they increase as RPM increases. You can also unplug it when it is running, if it dies- restart it, then see if power is back to normal.
I would also check the fuel pressure regulator
. If it was leaking, that would cause the very bad gas mileage, and could be the cause of a plugged catalytic converter.