Rough idle

Hi and thanks for using 2CarPros.

The residue you see is most likely the result of condensation created by the extreme cold and then warmer weather. How much fuel was in the tank? Has the check engine light come on? If you clean the throttle body of the residue, does it make any difference? Is the air filter dry and in good condition?

Here is a link that discusses a rough idle, possible causes, and how to fix them. Take a look through them.

https://www.2carpros.com/articles/engine-vibration-at-idle

Next, if the check engine light is staying on when the engine is running, here is a quick video that shows how to use a scanner to retrieve diagnostic trouble codes.

https://youtu.be/YV3TRZwer8k

I realize most people don't own a scanner. If you don't, most parts stores will scan it for free, so have that done and let me know what codes are found.

Start with these things and let me know the results. Also, if you have already done these things, let me know what you found and if any additional diagnosis was done.

Take care,
Joe