Symptoms if following are bad? B!tch Tube O-Rings, Intake Manifold Gaskets or FPR?

[IS300E30]

What would the symptoms be if one of the following is bad?:

1) Oil Return Tube aka crankvent tube aka B!tch Tube O-Rings?

2) Intake Manifold Gaskets?

3) Fuel Pressure Regulator?

Not if all are bad, but if #1 was bad was would the symptoms be? If #2 was bad, what would the symptoms be? If #3 is bad, what would the symptoms be?

[JehTehsus]

Depends on exactly what 'bad' means, but some of the following could occur (off the top of my head):

1. Essentially a vacuum leak, normally crankcase is under vacuum because air is pulled into manifold. Probably also leak oil, and by oil I mean oil and engine blow by.
2. Could be a vacuum leak post throttle plate, so constant high idle (like throttle is always open). Possibly also see some fuel leaking from injectors firing depending on how bad the gasket is.
3. Really depends on 'bad'. Like, bad as in major fuel leak? Symptoms could include an engine fire. Bad as in seized shut? Excessive fuel pressure, resulting in engine flooding or running very rich. Failed in such a way it isn't regulating? Low fuel pressure, engine running lean/not starting, etc.

[nando]

I know from experience, that a vacuum leak at the bitch tube (broken/missing o-rings) will cause a huge amount of oil to be sucked into your intake manifold and airbox.

[IS300E30]

The reason I brought this up is my symptom is:

Rough idle while in drive (what I would think a misfire would feel like), but extremely steady RPM and accelerates extremely smooth (only rough while idling in drive).

You can feel the vibration in the steering wheel, and you can really feel it when you put your hand on the Intake manifold (it feels like; shake, shake, smooth, shake, shake, smooth, shake, shake).

[ADEN]

Autos idles alittle more than manual first make sure your idle sits at 800rpm in P (google how to adjust idle) then if it is still shaking then i guess worn Torque converter is the cause of your issue.

[e30davie]

The first 2 are the same thing = vacuum leak. Fuel pressure regulator i would say you'd hardly get it to run if it was stuffed.

Any car with an ariflow meter is extremely sensative to vacuum leaks. even a hose clamp that isnt tight enough can and will cause a vacuum leak. and it will idle poorly but if its not that bad it will drive "fine". You need to systematically check every single point where air can get it in. There is no single answer.