I am new to the site and this is my first technical post. My wife and I purchased this 2005 Jag X-Type 3.0 in sept. 2011. After some time the engine light came on accompanied by a very intermittent surging problem on hard throttle from slower speeds. Taking off from a stoplight and mashing the gas will get her "bucking" like she has a Burr under her saddle! Ease into the throttle and she glides along smooth as silk. I am searching past posts for similar problems to get an idea of which direction to go with this. Any informed replies will be greatly appreciated!

 

There is a breather hose just to the left of the throttle body, it goes from the induction manifold to a valve in the top of the front cam cover. Pop that puppy off and look it over really well. It may have a nice split in it that creates a good sized vacuum leak at times. Could be the cause of the bucking you mention.

Cheers,

 

sounds like an air leak, check your int seals they are a common area or the brake booster check valve