Yo Ray,
Great!
Here we go...
Intake Air Temp (IAT); (Air Charge Temperature [ACT] prior to 1992)
The intake air temperature sensor (IAT sensor) (12A697) changes resistance in response to changing intake air temperature. The IAT sensor resistance decreases as the air temperature increases, providing a signal to the powertrain control module (PCM) (12A650) indicating temperature of the incoming intake air. On a diesel and MFI engine, the IAT sensor is installed in the lower intake manifold and in the air cleaner tube on SFI engines. by Ford
Could be age, blow-by, etc. There will always be some oil getting through the PCV valve in the form of condensates.
Testing by Ryan M @
http://www.fuelinjectedford.com/page29.html
Pull the EGR Valve and clean it and as much of the Intake Manifold passage.
Removal in 92-96; "...If you plan on replacing yours go buy a 1 1/16 wrench you'll need it to get the egr pipe off the egr itself..."
Source: by Bobby (blue)
Removal Tip in an 89 5.0; "...BE CAREFUL HERE. USE PENETRATING FLUID HERE PRIOR TO REMOVAL. I BROKE ONE ON MY LAST BRONCO AND I HAD TO BUY A NEW ONE FROM THE DEALER FOR ALMOST $100..."
Source: by Waltman
carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover.
..
Intake Manifold; I think that you need to enjoy driving your Bronco this winter and clean the manifold in spring. Whaddaya think Ray?
...
Now the 4x4
This is by Ford;
Four Wheel Drive (4X4) General Information, Operation & Troubleshooting TSB 92-1-8 ... Bronco, F Series & Ranger (partial); Includes Electric Shift On The Fly (ESOF) Troubleshooting; same for 87-96; exc for that in 87; power from Fuse 6 (15 amp) to "ELECT SHIFT CONTROL MOD" WHT-PPL and CB 12 (30amp) to "ELECT SHIFT CONTROL MOD" BLK-WHT; SEE A7 and A8 in the 4x4 diagram, it shows those two wires BLK-WHT as BK/W from SHIFT MODULE to P1 BATTY and and WHT-PPL as W/P to P2
http://redirect.viglink.com/?format=go&jsonp=vglnk_147043023689410&key=6ed47b392b9edfe394b9e89b72717104&libId=iri86z3r01000bgv000MA1km7nh0j30wfy&loc=http%3A%2F%2Fwww.fullsizebronco.com%2Fforum%2F21-noobie-bronco-tech-questions-flame-free-zone%2F218037-transfer-case-not-engaging-4x4.html&v=1&title=wire%20from%20transmission%20harness.%20-%20Ford%20Bronco%20Forum&txt=Four%20Wheel%20Drive%20(4X4)%20General%20Information%2C%20Operation%20%26amp%3B%20Troubleshooting%20TSB%2092-1-8%20for%2092%20%26amp%3B%20Prior%20Year%20Bronco%2C%20F%20Seri...&out=http%3A%2F%2Fwww.revbase.com%2FBBBMOTOR%2FTSb%2FDownloadPdf%3Fid%3D35193
See page 19 for the testshaft, that are for;
Nothing happens (dead system).
2. No range shift.
3. Attempt to shift into 4H from 2H or 4L results in the module clicking and chattering and the system stops in 2H.
4. At start up, the vehicle shifts on its own.
5. Indicator lights don't register the correct information.
6. Shifting on the fly isn't smooth and may require stopping in order to complete the shift.
I guess your issue is #1.
One significant excerpt is "...unbolt the motor and have someone activate a shift again. If the motor doesn't actually turn, it is malfunctioning and must be replaced..."
...
The 1356 Electric Shift Speed Sensor is in the tailhousing.
Some confuse this with rear axle mounted VEHICLE SPEED SENSOR (VSS).
...
1356 Electric Shift Motor Typical Failures & Prevention; "...Most units fail because of water or mud intrusion. Carefully inspect motor boot or protective coverings. Be sure connector seals can keep water and debris out. Check wiring harness and connector. Replace or repair wiring as necessary. After installation, periodically select 4-wheel drive mode to ensure operation when needed..."
Source: by CARDONE®
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Some brave soul rap the motor with a rubber mallet, while someone presses the button.
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1356 Electric Shift Motor Troubleshooting & Repair (travel stops)
Source: by Richard C (Bigric, Money Pit) @
http://www.supermotors.net/clubs/superford/registry/4584/21843-4
To view narrative, under Richard's name in upper left, click Select Alternate View; clicK Thumbnails + Captions
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Electric Shift Motor Replacement by autopartsdirect2you via Alex M @
http://broncozone.com/topic/15994-transfer-case-motor-installation/
1356 Electric Shift Motor Connector, Missing Pins, Bronco & Ford; "...Carefully record wire pin positions. Using a suitable tool, release each sensor wire pin. NOTE: Some harnesses may have a center pin as shown in the sample graphic. If there is a center pin, it must also be transferred. Install wire pins in the replacement motor connector in the same position as in the original motor connector until they snap in place. Note that the sensor and harness wire colors must match. Verify pin placement, then replace red locking tab. This completes wire pin transfer. The white pins are the ones for the speed sensor that need to be transferred..."
Source: by CARDONE®
Later,
Al