The silicone looks cool (it typically comes in red, blue or black), is easy to work with and will last forever, but rubber is much cheaper and will last for several years. You can't really go wrong either way but if you buy silicone it is worth buying from a reputable vendor, some of the lines on eB...

Did you check the gas cap seal for leaks? Possible source Leaking fuel tank, filler pipe, fuel tank filler cap, EVAP canister, EVAP canister shut-off valve or lines between these components. Blocked canister purge (CP) valve, EVAP canister, fuel tank pressure sensor or pipes between these components...

There should be another hard vacuum line that runs from the open nipple to the air door motor under the air cleaner

Excess air from the vacuum leak is unmetered, so your car runs lean, with high NOx emissions

The airbox is missing line 6 from this thread viewtopic.php?t=65002

Remove negative battery cable for 15-30min in order to reset fuel trims,perform a re-learn procedure and see if code comes back.

Sometimes ecu gets wrong data and learn bad things after reset...so you need to reset it again...this time give it a "hard" reset.