2006 Taurus SE transmission sound loss power

[zubiafj]

I recently purchased a 2006 Taurus SE, Standard 3.0 OHV, AX4N tranny I believe, pretty much the base car. The car runs, there are no service engine lights on at this time. I have a small idle issue where it sits at idle there is a small jump on the RPM gage. When driving the car at about 40 MPH there is a sound coming from the transmission and it seems like it looses power or like the overdrive is not kicking in? The car has about 66K miles, Any ideas on what to check or where to start? All the gears seem to hit smoothly with no issues but it does feel like its a loss of power? When I switched over to the D only the sound seems to go away but it still feels like a loss of power? Also sounds like a small exhaust leak too. Any ideas where to start on figuring out why the tranny is making this sound and loosing power????

[shorod]

You symptoms sound consistent with a vacuum leak, not a transmission issue. I'd suggest you carefully inspect all vacuum lines, including those for the PCV system, and replace any that seem soft, deformed, or cracked.

-Rod