Ok... your best bet to find this vacuum leak if there is any is going to be to have the intake smoked with a smoke machine. This is the easiest way to find a vacuum leak if there is any.
There is also a Technical Service Bulletin for this problem. Here it is.
1998-2000 Rodeo (UE)/Amigo (UA) models with 3.2L V6 engines
Some owners may comment on high/erratic idle and/or the MIL light on. In some cases, vacuum leak noise may be heard as well.
Possible Cause:^ There may be poor contact or loss of contact at various main ground points or electrical connections.
^ Power steering pressure switch may be shorted with debris.
^ Inlet manifold gasket may be leaking.
^ Broadcast code and calibration part number may need to be updated.
To correct this condition, follow the procedures outlined in this bulletin to determine proper diagnosing, inspection and correction of ground contact points for proper electrical contact, power steering pressure switch cleaning or replacement and power steering system flush, replacement of inlet manifold gasket, and/or PCM reprogramming
ALso, here is some info about your code
The throttle position (TP) sensor circuit provides a voltage signal that changes relative to throttle blade angle. The signal voltage will vary from below 0.6 volts at closed throttle to about 4.5 volts at wide open throttle (WOT). The TP signal is used by the powertrain control module (PCM) for fuel control and many of the PCM-controlled outputs.
Conditions for Setting the DTC
The ignition is ON .
TP sensor signal voltage is less than 0.22 volt for a total of 0.78 second over a 1.5-second period.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp (MIL) the first time the fault is detected.
The PCM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.
The PCM will use a default throttle position based on mass air flow and RPM.
Conditions for Clearing the MIL/DTC
The PCM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
A history DTC P0122 will clear after 40 consecutive warm-up cycles have occurred without a fault.
DTC P0122 can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.
Check for the following conditions:
Poor connection at PCM - Inspect harness connectors for backed-out terminals improper mating broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
The TP Sensor shares a 5 Volt reference with the EGR valve. If these codes are also set, it could indicate a problem with the 5 Volt reference circuit or components itself.
The TP Sensor shares a ground with the EGR Valve and the IAT Sensor
Damaged harness - Inspect the wiring harness for damage. If the harness appears to be OK, observe the throttle position display on the scan tool while moving connectors and wiring harnesses related to the TP sensor. A change in the display will indicate the location of the fault.
If DTC P0122 cannot be duplicated, the information included in the Failure Records data can be useful in determining vehicle mileage since the DTC was last set. If it is determined that the DTC occurs intermittently, performing the DTC P1122 Diagnostic Chart may isolate the cause of the fault.