Cleared all codes in the modules, thanks to Jim's advice and web site.
Road tested my car, still has the same problem, very low power, erratic idle and CEL is OFF.

Rechecked modules, no codes, all tested with no faults in system.
Inspected the wiring harness, found a very bad wiring harness. The wiring harness connected to the AIR MASS METER (wires near the connector) are touching each other, with no insulation. Temperorary repaired the wires and road test again, now, I can go over 40mph uphill.

Do you know where I can buy a new wiring harness for the AIR MASS METER?
Or buy the connector, so I can build a new harness.

Pcmaher is correct, the wiring harness is bad on the W140, I suggest the owner of the W140 inspect this harness. It probably has the same problem.