[Kamikaza]

Mine doesn't couph or splutter when P or N is selected.
The idling has actually got smoother after putting in new coilpack and spark plugs.
It is sitting around 700 rpm in P or N.
However, as soon as the gear is shifted to R or D without any acceleration, the engine starts to shudder, RPM drops to 500 and a lot of smoke comes out of the tailpipe (No blown Head Gasket here).
If this issue is related to the Intake Manifold Gasket, then idling should have been erratic or dropping.
If it is a matter of faulty Crank Angle Sensor, then it should be hard to start.
At the moment my bet is on O2 sensor because of some hesitation on acceleration with eventual stalling.
Again, no rough idle after having a new coilpack. Even in R or D, the RPM seems to be steady under 500.
If there was any vaccum leak, the idle will be fluctuated.
Any help will be much appreciated