2000 Jaguar S-Type p174 code

you can check the manifold intake with carburetor cleaner espricially manifold gasket. If there is a vacuum leak in some position after you spray the cleaner the rev will speed up

tried carb cleaner,didnt work. but the day before a "boot off" message came on i cant find this in the owners manual and my mechanic didnt know either any idea?

May I have your car fault detail for symptom?

car is running rough, plugs were changed,compression test good.mechanic thinks might be something mech affecting no 4 cylinder.