Aaron, I am reading your post, but the photo isn't showing. However, if you have any air leaks between the intake air meter (IAM) next to the air cleaner box and the throttle body (TB), then it will definitely will affect engine performance since the actual amount of air reaching the TB is not what the IAM has measured.

You did not indicate what model Jag you have, but it is common for the air intake snorkel to rub against the spark plug/coil covers and with age will wear throuw the bellows folds. You will have to remove the snorkel, turn it over, and bend to see any cracks. A quick remedy is to wrap electrical tape very tightly and several times around the cracked folds. Sometimes a more permanent fix requires gluing in some plastic tubing to act as a rub shield.

Good luck!
Bill
1969 E-type coupe, 1997 XK8 coupe, 2007 XKR coupe