Engine trim cover removal

Helping a neighbor with her '99 3800. How to remove the trim piece over the throttle body and injectors??

I see the rubber pin on the firewall side, but did not want to break the section that seems to be fastened under the oil fill tube neck.

Guidance appreciated.

Open the oil filler neck, when it reaches the stop point, continue to turn it, this will remove the filler neck, whick is attatched in the same manner as the filler cap. once off, carefully(so as not to allow dirt to enter the engine) remove the cover. Th filler neck may or may not be replaced, it's up to you.

Thank you for the help. Mission accomplished.