First off it sounds like your starting to get it sorted out...something i have found in my past work has been a weak magnet for the cam sensor located in the cam gear of the timing chain...i have had these cause me cold idle issues and not trigger any codes (you will need a digital graphing scope to look at the signal) it should be a nice clear waveform.
check manifold vacum and post up i am curious myself whether it is low or not as this will determine what direction your diagnostics takes.
also i saw the posts on the PCV valve and would like to clear up some misconceptions...
there are three flow positions in a PCV valve system, closed, small orifice (spring fully compressed) and large orifice.
this is a section from one of my IM240 emissions tech manuals (on DVD
When the engine is running, intake manifold vacuum is supplied to the PCV valve. This vacuum moves air through the clean air hose into the rocker arm cover. From this location, air flows through cylinder head openings into the crankcase where it mixes with blow-by gases that escape from the combustion chamber past the piston rings. The mixture of blow-by gases and air flows up through cylinder head openings to the rocker arm cover and PCV valve.
Intake manifold vacuum moves the blow-by gas mixture through the PCV valve into the intake manifold. The blow-by gases are then moved through the intake valves into the combustion chambers where they are burned. Since blow-by gases contain hydrocarbons and other pollutants, these gases must not be allowed to escape to the atmosphere.
The PCV system prevents the escape of blow-by gases to the atmosphere. On many engines, the PCV system delivers blow-by gases to one location in the intake manifold. This type of system may not deliver these gases equally to all the cylinders.
This action may result in an air-fuel ratio variation between the cylinders, which results in rougher idle operation. Some engines, such as the Ford 4.6 L V8, have passages from the PCV valve system through the intake manifold and gaskets that supply blow-by gases equally to each cylinder, resulting in smoother idle operation. PCV Valve Position with the Engine Not Running The PCV valve contains a tapered valve. When the engine is not running, a spring keeps the tapered valve seated against the valve housing.
PCV Valve Position During Idle or Deceleration
During idle or deceleration, the high intake manifold vacuum moves the tapered valve upward against the spring tension. Under this condition, there is a small opening between the tapered valve and the PCV valve housing. Since the engine is not under heavy load during idle or deceleration operation, blow-by gases are minimal and the small PCV valve opening is adequate to move the blow-by gases out of the crankcase.
PCV Valve Position at Part Throttle
The intake manifold vacuum is lower during part-throttle operation than during idle operation. Under this condition, the spring moves the tapered valve downward to increase the opening between this valve and the PCV valve housing. Since engine load is higher at part-throttle operation than at idle operation, blow-by gases are increased. The larger opening between the tapered valve and the PCV valve housing allows all the blow-by gases to be drawn into the intake manifold.
PCV Valve Position During High Engine Load and Engine Backfire
When the engine is operating under heavy load conditions with a wide throttle opening, the decrease in intake manifold vacuum allows the spring to move the tapered valve further downward in the PCV valve.
This action provides a larger opening between the tapered valve and the PCV valve housing. Since higher engine load results in more blow-by gases, the larger PCV valve opening is necessary to allow these gases to flow through the valve into the intake manifold. When worn rings or scored cylinders allow excessive blow-by gases into the crankcase, the PCV valve opening may not be large enough to allow these gases to flow into the intake manifold. Under this condition, the blow-by gases create a pressure in the crankcase, and some of these gases are forced through the clean air hose and filter into the air cleaner. When this action occurs, there is oil in the PCV filter and air cleaner. This same action occurs if the PCV valve is restricted or plugged.
If the PCV valve sticks in the wide-open position, excessive air flow through the valve causes rough idle operation. If a backfire occurs in the intake manifold, the tapered valve is seated in the PCV valve as it is when the engine is not running. This action prevents the backfire from entering the engine where it could cause an explosion.