The car has rough idle and turns off after warming up for about 10 minutes

real bad, the cylinders end up getting so flooded it just shuts off. So does that means its an electrical issue. Also at highway speeds it runs perfect, this only happens when idling. The problem was not as bad a few months ago but sense then i drove it on two 600 mile trips (never overheated) which amplified the symptoms to what it is now.

hi amartin, My xj6 has same exact problem you describe. Rough idle, rises and falls every few seconds, and engine dies at red lights. Though your post was in 2011, do you recall to settle this cat to smooth sailing? If so how you fix it? I've changed fuel filter, fuel pump, spark plugs, oil filter, oil, and today the Idle cleaned carbon off of it. I'm hoping it is Mass Air Flow Sensor or Throttle Body cleaning. Help solve this, same as yours-frank68