I was told that brake lights stay on even though I am accelerating. Mechanic thinks it is power brake booster. Quoted $1100 “hoping” that resolves issue. Any thoughts on a 1994 XJS I6 engine?

 

You mean the brake lights on the back of the car?

IMO that's not to do with the "power booster" (whatever your mechanic means by that). Sounds far more likely to be a maladjusted switch on the brake pedal. A much cheaper one to check first.

Good luck

Paul