My 1998 XJR generally runs very well but in the past week I've had something odd happen three times:

1. At highway speed and I let off the throttle to slow down for an intersection. As I approach the intersection, no response from the throttle. The car slows down, going into the lower gears. Once stopped the throttle responds like normal and I take off.
2. Coming down a hill at highway speeds, I use the J gate for engine braking before my exit. Again, end up with no throttle response. Put it back in D, then N, then D and it works fine.
3. Coming up the same hill this morning, I accelerate at WOT up to 140 km/h. Let off the gas, again no throttle response. This time the engine stalls. I put it in N, stop, and then restart the car and it is fine.

Seems like a fuel delivery issue to me but I'm not sure. Any ideas of where to start looking?

 

I would start with a new fuel filter, a clean throttle bore and plate, a clean MAF, a new air filter, and a reading from OBD.

 

We played this game a few decades ago when I worked at the dealer.

 

I would look into the throttle body relay as a possibility, unplugging all 3 TB connectors (they’ll shatter like thin glass) and see if there’s any loose, pushed in pins or corroded pins.

I wrote this post several years ago and it’s something that you should at least look into. I’m going to say that it’s not likely your problem but, something to think about. Post 16 has the outcome of the issue.

https://www.jaguarforums.com/forum/x...ncerns-159443/