Why!?
It's blown. There should not be any suction at all from there.
You mean when the PCV valve is is disconnected, right. There absolutely should be a vacuum on the breather ... if the PCV system is working correctly, that is. That's what its there for.
Wow ... lucky day ... posted this today for another problem. The PCV valve is right there at the rear of the valve cover.
https://dodgeforum.com/forum/1575973-post4.html
https://dodgeforum.com/forum/1575973-post4.html
Oops ... my bad, the "valve" in the picture is the breather. The PCV valve IS on the left (Sorry Ram2K1). 
RAZRAM: In case you're still confused ... the official procedure for a plenum gasket inspection follows:
Inspect the Positive Crankcase Ventilation (PCV) valve. Shake the PCV valve to verify that the pintle inside of the PCV valve is free. Replace the PVC if the pintle is not free.
If the intake manifold plenum pan gasket is leaking, an additional vacuum source will be created inside of the engine at the location of the pan gasket leakage.- Engine combustion blow-by gases, oil vapor, and air from the crankcase filter/breather may be drawn past the leaking pan gasket and into the intake manifold. In most cases when this condition occurs, an engine at idle will create the highest vacuum and lowest amount of engine blow-by.
1. Allow the engine to reach normal operating temperature.
2. Stop the engine.
3. Disconnect the breather hose from the air cleaner.
4. Attach a vacuum I pressure gauge to the end of the breather hose (Figure 1).
5. Disconnect the PCV valve hose from the intake manifold.
6. Seal off the intake manifold PCV valve hose port opening.
7. Seal off the open end of the PCV valve hose (Figure 2).

NOTE: DURING THIS DIAGNOSIS, IT WOULD BE NORMAL FOR THE ENGINE TO DEVELOP PRESSURE WITHIN THE ENGINE CRANKCASE. THIS IS DUE TO -THE NORMAL PROCESS OF. EXHAUST BLOW-BY- GASES- LEAKING PAST THE ENGINE PISTON RINGS AND ACCUMULATING IN THE ENGINE CRANKCASE. DO NOT ALLOW MORE THAN 3 PSI (20.7 kPa) OF PRESSURE TO BUILD WITHIN THE ENGINE WHEN PERFORMING THE FOLLOWING DIAGNOSTIC PROCEDURE.
8. Start the warmed engine and observe the vacuum gauge.
9. Allow the engine to idle for approximately 30 seconds. Do not allow more than 3psi (20.7 kPa) of pressure to develop in the engine crankcase.
10. If the attached vacuum I pressure gauge does not indicate that a vacuum is present in the engine crankcase, then the intake manifold plenum pan gasket is good and no further internal engine vacuum leak diagnosis is required.
11. If an internal vacuum leak is present then perform the Repair Procedure.
I really doubt you have a blown gasket ... your power would be way down.

RAZRAM: In case you're still confused ... the official procedure for a plenum gasket inspection follows:
Inspect the Positive Crankcase Ventilation (PCV) valve. Shake the PCV valve to verify that the pintle inside of the PCV valve is free. Replace the PVC if the pintle is not free.
If the intake manifold plenum pan gasket is leaking, an additional vacuum source will be created inside of the engine at the location of the pan gasket leakage.- Engine combustion blow-by gases, oil vapor, and air from the crankcase filter/breather may be drawn past the leaking pan gasket and into the intake manifold. In most cases when this condition occurs, an engine at idle will create the highest vacuum and lowest amount of engine blow-by.
1. Allow the engine to reach normal operating temperature.
2. Stop the engine.
3. Disconnect the breather hose from the air cleaner.
4. Attach a vacuum I pressure gauge to the end of the breather hose (Figure 1).
1 - VACUUM / PRESSURE GAUGE
2 - BREATHER HOSE
3 - VALVE COVER BREATHER HOSE PORT
2 - BREATHER HOSE
3 - VALVE COVER BREATHER HOSE PORT
5. Disconnect the PCV valve hose from the intake manifold.
6. Seal off the intake manifold PCV valve hose port opening.
7. Seal off the open end of the PCV valve hose (Figure 2).

NOTE: DURING THIS DIAGNOSIS, IT WOULD BE NORMAL FOR THE ENGINE TO DEVELOP PRESSURE WITHIN THE ENGINE CRANKCASE. THIS IS DUE TO -THE NORMAL PROCESS OF. EXHAUST BLOW-BY- GASES- LEAKING PAST THE ENGINE PISTON RINGS AND ACCUMULATING IN THE ENGINE CRANKCASE. DO NOT ALLOW MORE THAN 3 PSI (20.7 kPa) OF PRESSURE TO BUILD WITHIN THE ENGINE WHEN PERFORMING THE FOLLOWING DIAGNOSTIC PROCEDURE.
8. Start the warmed engine and observe the vacuum gauge.
9. Allow the engine to idle for approximately 30 seconds. Do not allow more than 3psi (20.7 kPa) of pressure to develop in the engine crankcase.
10. If the attached vacuum I pressure gauge does not indicate that a vacuum is present in the engine crankcase, then the intake manifold plenum pan gasket is good and no further internal engine vacuum leak diagnosis is required.
11. If an internal vacuum leak is present then perform the Repair Procedure.
I really doubt you have a blown gasket ... your power would be way down.

I know this, before my plenum repair: lots of suction through the fitting on the Driver's side. After plenum repair: no suction at all. The blown gasket was causing a vacuum in the crankcase.



