Rough idle after cold start, only in park (1 Viewer)

[BrownAce]

When I start my 100 in the morning I get a slightly rough idle but I only notice it when it's in park. As soon as I put it into reverse it seems to go away. If I put it into park again I still notice it but it goes away after I drive for 10 minutes. It doesn't even need to be fully warned up and it seems to go away.

No engine codes. Any ideas if what to check? Its not that rough but it's noticeable compared to the smooth running after it warms up . I live in Southern California, it's not cold in the morning at all. 65ish

Cracked coil? Vacuum leak?

 

[jsloden]

I would lean towards cracked coil. Mine was doing the same thing. I wasn't able to figure it out until it got considerably worse and started doing it while driving. After you start the car unplug the coils one by one and see if you can pinpoint the problem. FYI mine never threw a CEL the entire time.