I'm having a problem with low vacuum at egr valve. All rubber hoses were replaced. At the egr valve and on the turbo side. When measured, vacuum holds at 5 mmHg at idle at the egr transducer... 15-20 mmHg is needed to open egr valve. There is 25 mmHg vacuum at the brake booster. There is good vacuum just not at egr or waste gate transducers. Vacuum line t's off into the firewall on passenger side. Vacuum diagram in the engine compartment states "other users" for that line. Where does that line go? My ac has been acting strange too. I am puzzled and tired. Don't feel like pulling my dashboard out just yet. Please help... Thanks.