Volvo: 92 Volvo 960 with Idle Control Problem., bosch motronic, driver circuits

Question
Would like to present you with a problem I am having with my Volvo in hopes that your electronic experience can be of assistance.  I believe my problem to be electronic / electrical in nature but I will let you be the judge of that.  To begin, some background on my vehicle, I own a '92 Volvo 960 automatic with 146K miles and a Bosch Motronic 1.8 system.  I have recently been experiencing drivability problems due to a lack of idle control.  This is particularly pronounced when the vehicle is stopped and in the drive shift position.  The condition has now deteriorated to the point where the vehicle stalls while previously it just maintained a low idle of approximately 500 RPM.  I understand that the idle speed should normally be between 700-800 RPM.  I have also accessed the data link connector (DLC) in the engine compartment and have extracted the trouble code of 2-3-3 which  corresponds to a long-term idle air trim fault.  I next inspected the idle air control (IAC) valve thinking this was the source of the trouble.  I tested the coil driver circuits per my Chilton manual and found the valve to be within specifications concerning the resistance values at each of the connector pins.  I then tested the voltage lead - this is where this repair manual falls short of an exact explanation.  The procedure outlined in the manual begins by asking the negative battery terminal to be disconnected, standard operating procedure used throughout this manual regarding electrical connections.  The next step of turning on the ignition to ON, however, does not make sense in order to measure the voltage at the lead terminals so I did not break the circuit.  The voltage at the center terminal #2 measured the approximate battery voltage.  The lead failed the next two checks of the signal return and the ground circuit.  The signal return at terminal #1 measured approximately 10 volts where the specification should be 6-8.5 volts.  The ground circuit at terminal #3 also did not read continuity.  This lead me to believe that the problem was with the circuit starting from the voltage lead connector.  I traced the wiring harness under the intake manifold back to the junction box adjacent to the driver's side wheel well.  I back-probed the red/gray and black/orange wires corresponding to terminals #3 and #1, respectively, and found that there was continuity from the end of the voltage lead to the junction box.  At this point, I exhausted my both my level of expertise and the detail to which my repair manual details the wiring diagram.  Also, of interest is the simultaneous problem I am having with the speedometer which moves erratically even when the vehicle is stationary.  This lead me to believe I had a short circuit so I checked all of the fuses at the dash panel but all were intact.  I thank you in advance for any information you may provide to correct this problem.  

Answer
Hello,
my first question and my first recommendation will be about timing gear adjustment: Did you replace the timing gear? Please, check the timing gear setting...
And, please be sure about if there is air leakage at inlet side or exhaust side, maybe there is one burst pipe or cracked pipe, check all of them.
And, after all these, again everything seems okay but there is problem, you should test the car with a new Mass Air Flow sensor, it maybe defective.
Regards//Vedat...