Cylinder one misfire?

Hello, if you pull the number 1 spark plug out what is the condition of the plug, is it wet with fuel, black with carbon build up, or more of a white coloring? If your oil is yellowish and smells like gas, then most likely you have either a fuel injectors that is staying open more than it should, therefore allowing too much gas into the cylinder and that is causing the misfire, or the piston rings for that cylinder have gone bad and you are getting a lot of blow-by and gas is entering into the oil that way. Check the spark plug first, take a picture and post it here. If you replaced that fuel injector, why would it need to be cleaned? Thats not logical reasoning, I'm not sure why they told you that. Another thing, did you put in an aftermarket fuel injector? Not one from the dealership (OEM)? Fuel injectors need to be spraying equally, when we do a fuel injector balance test, they need to be within 1 to 2 psi of each other. If you put an aftermarket injector in it may not be spraying correctly but doing an injector balance test is the only way to know if they are all spraying the same amount.
Smell the oil too, does it smell like gas? If it does, you may want to do a compression test on that cylinder to see if there is an issue with the piston ring. I will post instructions on doing an injector balance test, you will need a fuel pressure gauge to monitor fuel pressure during the test, and a fuel injector pulse tool which you can get on amazon for around $30.00.
You can also swap over the spark plug and fuel injector to a different cylinder and see if the code goes to that cylinder or stays at the number 1, this can help rule out some components when diagnosing a misfire.

Below is the Fuel injector pulse tool, it hooks up your car battery and allows you to pulse the fuel injector a certain amount just like the engine computer does, when you have a fuel pressure gauge hooked up to the fuel rail, you will monitor how much the pressure drop is for each fuel injector.

Turn the key to the on position, not engine running. This will prime the fuel system up to operating pressure, then pulse the injector, write down how low the pressure went. Then move on to the next fuel injector and do the exact same thing.

So, for example, key "on" your pressure will be 50 to 60 PSI, pulse the tool and the pressure will drop around 15 to 20 PSI. Then write down the current pressure (35 PSI or whatever it is). Hook up to the next injector, key "on", pulse the tool. write down the results and so on. If any fuel injectors are clogged or allowing too much fuel, there will be a difference in your test results, pinpointing the issue. After you do all four cylinders start the vehicle to clear out all the fuel before retesting.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

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

That's okay. Look at what I posted above. It's all the instructions on testing the fuel injector. If you have any questions when you get home, just ask. The fuel injector test will tell you all you need to know about the injectors at this point.