Depends on what it is..It could be a vacuum line (several to look for) it could be the O rings on the Throttle control valves.....Actually the parts are cheap..it's the dealer's labor and Dianostics that will cost a bit..estimate under $300.00 USD to fix all of the above.

Check this vacuum line for the brake booster



And there is a big fat hose that goes into the front of the engine (Radiator side)

These are the throttle Control Valves..Replace both O rings (one in each)

 

Thanks Bo..I don't know why I wanna keep calling them Throttle control valves..Beats me where I heard that..[&:]

 

There's also a tube on the top of the engine that gets cracked down the middle (located under the black plastic cover on the 3.0/not sure what year/engine you have)


(If you were wondering it is the tube running front to back and is to the left of the intake tube.)

 

Yeah thanks..Good one..that's the Fat oneI was talking about

 

I feel bad for how dirty it was under there...i never removed it before then...[:'(]...the engine was clean everywhere else...

 

Hi Racer, that was very nice of you. I'v printed the list and i'll keep it in my pride and joy 02 x that way, if it takes a dump down the hiway on the way to work, i'll know whats up. well done.