I do not have my A/C hooked up, I don't even have a plug on the inlet pipe near the firewall. Do I have a vacuum leak because of this?

 

Probably not. The source for the HVAC control vacuum is the engine. There is no "return" line.

 

I got 1 line for vacuum booster and one line for FPR, what is the third line for?

 

Just behind the vacuum hose bibb for the FPR is another that is supposed to be connected to the HVAC/cruise vacuum supply:



If there is no line or cap there, you WILL have a vacuum leak. I thought you were asking about abandoning the line at the firewall.

 

Thanks for info. My line is hooked up so thier shouldn't be a Vacuum leak. Just thinking of capping it of cuz I am deleting my AC. I have a Superram so things look a lot different.

 

Another possibility to consider is in your throttle body. If the butterfly pin or throttle pin that go through the housing are loose at all you could be leaking vacuum from there. How much or what effects that would have I don't know...but 'm told those moving parts wear easily, and without a rebuild they can leak pressious vacuum.