I have a 2005 Elantra hatchback with 138,000 miles. I have owned the car for about 8 months and since I have owned it the car has a rough idle while in park and gets worse when you put it in gear. I have changed the IAC valve, checked the pcv, that checked good. Changed spark plugs and spark plug wires, I also replaced the evap canister due to other issues. When I bought the car I had a check engine light for the downstream 02 sensor which the tech cleared the code and I did not change the sensor since the check engine light never came back. My RPM’s also will surge up and down the go from about 900 to 11 or 1200. It was worse before I replaced the iac valve. Anyone have any ideas?