I have 2001 jaguar 4.0 vandenplas..Runs great but when stopped at traffic light in gear with foot on brake there is a misfire, if I put it in neutral then it stops, otherwise car runs great

 

Does the check engine light come on ? If so, you need to read the codes. If not, try cleaning the MAF and the throttle body. There are utube videos on this, but the main thing is to use cleaner made for MAFs and one made for throttle bodies. The throttle body has a finish on it that you don't want to damage and the MAF should only be cleaned when cold with MAF cleaner. You could also clean the part load breather and check for intake air leaks.

 

Start with the simple stuff -- check to see if the air filter box and tube are installed properly and that there are no cracks in the air tube. You just might get lucky and not have to spend a lot of time on it.

Cleaning the MAF and throttle body is pretty simple, and gives you an excuse to bond with your car.

When checking the part and full load breathers, be careful not to damage the connectors. Try a search on this forum for cleaning these and you'll get a lot of great info.

Good luck.

 

I would suggest it is a vacuum leak in the hose to the brake booster, as you say it only occurs with foot on brake.

 

thanks everyone for the advise, will do!!!!!
bobby