I have a 2004 Dodge Stratus sxt 2.4L SOHC. After changing my oil and air filter my car started idling erratically while in drive. It was alternating between 400 and 1000 rpms. It happens at intersections. I rechecked the oil level, plug and filter. All ok. I originally had a check engine light on, which was the upstream Oxygen sensor. That has been replaced. I replaced spark plugs, and wires. I noticed that there was oil in spark plug tubes, and on the threads of the #2 spark plug, but not on the ignitor part. I changed the valve cover gasket and spark plug tube seals. I put 1 pint of seafoam in gas tank, and 1 pint of seafoam in crankcase. It is no longer alternating rpms like it was originally, but does seem to drop down to about 400rpms and then go back to about 800rpms when first put into drive.