Hi guys i need help on my jag xtype 2002 mdl. i am having a jerk on 3000 rpm, my brake intermittently going stiff but more pronounce when newly start even after around 40 minutes of use, also i can here a popping sound on intake air box, i know it seems i am having a problem with air leak but no luck on finding it.... i have replaced TPS, PCV or ICV , replaced new brake booster, replaced brake booster vacuum hose, replaced all spark plugs, replaced three of the ignition coil under the intake manifold, resealed IMT oring (2x), resealed the hose that connects to the intake manifold, resealed the intake manifold (3x) , borrowed vacuum valve from another unit, but still having no luck!!! what the hell seems to be wrong with this car....i know a lot of gurus here kindly help me to tame this cat!

 

Is the car producing any codes?

 

A smoke test is probably next.

 

sorry but i am ignorant of doing a smoke test. how does it goes?