I have been experiencing a problem with my Jaguar X-Type (2006). I just had a minor service done (oil change, spark plugs). Subsequently, it has a slight jerk on start-up, and feels as if it is sucking in air. Once you drive it for a little while it is fine. Took it back to the garage and they cannot find any faults. On two occasions, when I put it into gear (reverse and drive) the "sucking in air " sound was louder. Back in "Park" it was better. Any suggestions?

 

You could try power braking it and see if a friend or you hear it while the other power brakes it. To power brake it apply the hand brake, step on the brake and put the car in drive, and pulse the accelerator without letting go of the brake.

If not you could also try this checklist: jaghelp.com: That pesky rough idle

Also get a code reader and check for faults to make sure you don't have any. Then look at the trims, see if they are close to 0% like they are suppose to. If they changed the spark plugs in the v6 they probably removed the intake manifold, did they put new seals?