Welcome back.
There is a chance that it is related to an engine vacuum leak or the idle air control valve (IAC). The IAC is responsible for maintaining the engine's idle speed. You mentioned that the idle has been higher than normal. I attached a picture of possible causes. However, there is a list. If the check engine light is on, you should scan the computer to determine if there is a trouble code stored which should indicate where the problem is coming from.
Here is a quick video showing it being done. Most parts stores will do it for you for free.
https://youtu.be/YV3TRZwer8k
If the check engine light is not on, most likely, there will not be codes. Were you able to test any of the items I mentioned in the first post? There are so many different things which can cause it. Things as simple as a plugged air filter can cause the engine to run rich or even not at all. A weak battery can cause the idle issue.
Let me know.
Joe
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Saturday, August 25th, 2018 AT 6:27 PM