After being plagued with the P0171 code and restricted performance while idling forever now. It turns out the O-Ring on the dipstick was bad and creating a vacuum leak.

all is well now. Gonna report back after a handful of miles but it seems to be doing great! No CEL and idle is smooth as butter again.

 

Which O-Ring please? The one actually at the top of the dipstick, or the O-Ring at the bottom of the dipstick shaft?

 

Right under the dipstick handle, where it slides into the tube, is a small O'ring.
The dipstick on my 04, was always sticking up about a half of an inch.
Guessing that the internal pressure of the motor was pushing it up.
Stays all the way down in the tube now, since replacing that O'ring,
Still waiting for the comprehensive components to clear though, its been over a year now.
Thought maybe that the O'ring, just MIGHT be the problem, but it wasn't.
Fortunate that it will pass the emission check, with this one item not yet cleared.

 

If the crankcase has pressure that is the issue. Pull oil fill cap and check with engine running. Place your GLOVED hand over hole to check.

 

the one that seals the dipstick in the tube. Should be at the base of the handle where it meets the tube.

 

Do not know just why it was not staying in the tube all the way.
The car runs like a top, uses no oil, & its good on gas.