I have a 1997 Jaguar XJ6. It is a great car, has a 140,000 on it and i have had few issues. It start leaking oil badly, took it to the shop and it needed a head gasket. it was leaking up front.

now that i have the car back it is doing something new. at idle and idle only, the car will run from 20 to 50 seconds smooth as silk, then it will literally skip a beat, almost as if it is being shut off and then it come right back like nothing ever occured.

it seems to only do this when it is warm. Also, you can run it up to 3000 rpm and it never misses a beat. this only happens at idle?

any idea's what is going on?

 

Start with the basics, give it some new spark plugs and visually inspect the coils. I would also clean the maf and the cps