Strange that the failure is intermittent. That would indeed not indicate a vacuum leak. Did you see the STFT figures without the failure? I don' t believe that an O2 sensor would fail one moment and thereafter is ok again. I would still have a look at the inlet manifold, its where the air enters the engine. Just check with care the whole inlet system from the filter until the cylinder head. Check for loose hoses, cracks and missing gaskets.
JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.
Thank you for you help.
Problem solved, O2 Upstream sensor dies yesterday and truck does not stop failing.
Hook the scanner and read the Voltage of the sensor with not fluctuation.
I replaced the sensor (Delphi Brand) and the truck start working like new.