RPMs running high; when I accelerate the RPMS don't go down...the remain steady on 2003 Mitsubishi Eclipse

I just replaced both O2 sensors and my MAF sensor. The car is not running correctly. When I shift from 2nd to 3rd the RPMs remain at 3-4 and don't go down when shifting. It's like my engine reves up, but the car remains the same. No get up and go anymore

Asked by for the 2003 Mitsubishi Eclipse
Could be a couple different things; commonly the Idle Air Control Solenoids go out and can cause these symptoms. Or your throttle body could be sticking.
Is this going to be a costly repair?
Throttle body cleaning is not costly. And may be recommend in addition to other repairs if necessary. I'd recommend diagnostics so you don't waste time and money guessing on repairs.