well for starters i would change the timing belt because it's due for a change every 60K. the fuel filter is also supposed to be changed every 60K as well. the following is due every 30K: coolant flush and change the thermostat (not needed but recommended), transmission fluid change/flush and transmission filter change (if equipped), if it's a manual the gear oil in the transmission and diffs and transfer case (if 4wd) don't need to be changed for 50K but if it's never been done i would change it out, plugs and wires are due for a change at 30K, air filter is due for a change at 30K (or as needed), and i would also do an oil and filter change. that should get your sportage running the way it should.
i have a guide posted
here if you would like more info on what you should do as far as preventive maintenance.
Performance boost for 01 Sportage
Linear Mode
