Rough idle

I would try some Top Tier detergent fuels like Sunoco Ultratech, they are packed with more detergents than standard fuels that only meet the minimum EPA requirements.
Has the air filter beem changed when needed.

243winxb said:

I would try some Top Tier detergent fuels like Sunoco Ultratech, they are packed with more detergents than standard fuels that only meet the minimum EPA requirements.
Has the air filter beem changed when needed.

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I've changed the cabin and engine air filter twice in the last 2 years but ill try some top tier detergent like you suggested, thank you .

Reynag said:

Recently my 2013 crosstrek started idling rough at stop lights.Sometimes it runs fine and other times it struggles with power . I had the spark plugs and serpentine belt changed recently but that didn't fix it.

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Are there any Diagnostic Trouble Codes stored in the Engine Control Unit?
According to the service manual for the 2014 Crosstrek, top causes of rough idling are (1) a loosened or cracked intake duct, (2) a loosened or cracked PCV hose, (3) a loosened or cracked vacuum hose, (4) incorrect valve timing, and (5) an evaporative emission control system malfunction. Items (1), (2), (4), and (5) are also top causes of low output, hesitation and poor acceleration.
There are about a dozen other items that sometimes cause rough idling.

You might want to check out MrSubaru1387's youtube channel about cleaning the throttle body and doing a top end cleaning. Seems to help idle issues.