Hi, I have a 2013 XK 68k miles. Got the limited performance light while exiting the highway. Car ran rough at the stop light and smelled gas. About 30 seconds later, gas smell went away, light went off and car ran normal. Pulled codes P300, P302, P304 & P306 which are misfires. Changed the spark plug and coils, started the car. Noticing a short hiss coming from the front of the throttle body when the accelerator is tapped. Any idea what this could be? I'm assuming a leak but nothing visibly cracked or worn.

 

Doubt changing all the spark plugs and coils had any significant effect.
How did the plugs look?
Definitely a leak.

 

Something broken when removed or reassembled. If it’s intake related you’ll
like get a lean code. I’d begin removing and or inspecting any hoses or instakes and then reassemble. The throttle body hoses and breathers need to be firmly seated or they may hiss.

 

The plugs were dirty but not horrible. I agree with it's likely a leak. Now we just have to find it!