I recently changed the spark plugs and have not yet changed the spark plug wires. My car is idle hunting, RPMs will be around 800, when in neutral, to 2500 and they will just sit at 2500 for a while sometimes until I intervene and either turn the car off or put it into gear and creep forward. It started doing this, it gave the error P0300 - Random/Multiple Cylinder Misfire Detected, so I decided to start with the spark plugs. My idle has smoothed out, it doesn't feel as rough, however the RPMs are still out of whack. What could the issue be?
My car has 160000 miles.
My car has a manual transmission.
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