2010 Ford F-150 STX 4.6 purge valve solenoid?

I notice it's time to change my purge valve solenoid when the car shuts off when stopping. No engine light comes on. I change the selonoid and it runs again for about 15k miles and it goes bad again.

Do I need to change the big canister (charcoal) related to this valve selonoid? Will that fix it or what do you suggest.

Issue with the Aux input in my car?

So I'm currently having an issue and no matter where I look there's no answer online, which is rather frustrating. Firstly, I have a Ford F-150 Lariat 5.4 Triton. On the top of the radio it says "Line-In" where I'm able to plug in one of the Auxillary cord and the other end into my phone. On the radio, it has an Aux button. When I press it, it has three options labeled "Sat 1, Sat 2, Sat 3." Though, no matter what option I choose, no sound plays through the speakers and a message is displayed on the screen and says "Call Sirius" And displays their number. When I called them, they told me to buy a subscriton in order to "activate their services." So, does that mean I have to pay in order to even use the Aux or am I doing something wrong? I have an iPhone 8 Plus if that helps. The aux cord does work because I tried it in my mother's car and it works fine there.