Engine runs on after I let off the gas
I have a 2004 PT Cruiser. It runs fine, doesn't burn oil but there is a serious problem. While driving and approaching a stop, the engine continues to run at high RPM's even after you let off the gas. It remains running at a high RPM for 4-6 seconds after you release the accelerator. After that, it returns to a slightly higher than normal idle speed. What could be causing this?