Check engine misfire?

2011 SUBARU IMPREZA
151,300 MILES • 2.5L • 4 CYL • 4WD • MANUAL
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ELIZABETHLM
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Head gasket, timing belt, water pump replaced. Feb. 2021. Check engine light one week later- misfire code, replaced spark plug. a month and a half later timing belt tensioner defective, replaced. Had to add coolant in less than a week after that. Check engine again 2 days ago.. misfire diagnosed as bad valve guides in cylinder heads...
Would this have been noticed when the head was repaired?
Should I get a second opinion?

The whole time since the original head gasket repairs its had a very rough idle, for months. Gas consumption has been very high the past week.
May 20, 2021 at 6:25 AM
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STRAILER
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Yep, it sounds like the heads needed a valve job and they missed it. To confirm the issue we need to remove the spark plugs and do a compression test. this will tell us if you have a low cylinder and if so the engine will need to come back apart. Also when the spark plugs are out check the color of each to see if one looks different than the rest this will be the troubled cylinder.

https://www.2carpros.com/articles/how-to-test-engine-compression

and

https://www.2carpros.com/articles/how-to-change-spark-plugs

Let us know what happens and please upload pictures or videos of the problem.
May 21, 2021 at 9:57 AM
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ELIZABETHLM
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Thank you!
I am not personally working on my car, but dealing with a shop that is causing me headaches.
They quoted me almost half of what the head gasket/timing/water pump costs...when this could have been prevented. And the owner believes that this problem has nothing to do with anything they have worked on. Sounds fishy to me.

Again! Thank you.
May 21, 2021 at 3:15 PM
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STRAILER
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yep, ask them if they checked the valves for leaks before they reassembled the engine?
May 23, 2021 at 10:08 AM