Good morning. My 2001 Galant has decided to start misbehaving lately. When it first starts up and heads out, it works fine. Once I get to that first STOP sign or red light, the car sputters and runs rough. It will shut off unless I put the shifter into NEUTRAL or PARK during the sputtering. Once in NEUTRAL/PARK, the sputtering normally goes away. After that first round of sputters, the car seems to be fine until it has been off for an extended period of time-- maybe an hour or so. The same thing occurs with that first round of idles in DRIVE after being off for awhile.
SO... I have replaced two of the spark plug wires-- the far left and far right-- and found a minimal amount of oil on the spark plug wires when I removed them for replacement. I have not yet replaced the plugs-- last replacement was about 85,000 miles; I'm at about 160,000 now-- but plan on doing that today. I also added a fuel injector cleaner to a full tank of gas yesterday. Just had an oil change before this started. Drove it pretty hard after the oil change-- a few hundred miles through mountains over one weekend. Air filter looks clean. No CHECK ENGINE light has shown up yet. Thoughts? Thanks in advance for any assistance.