Error codes...

3 weeks ago, the 4X4 shift module wouldn't allow 4WD lo. Went back to 2lo by default. 4hi engaged okay, but wouldnt leave first gear. Then, the gauges started blinking out while on the road. Then they'd go out for a minute or so following start-up. Now it's in limp mode (finally a constant SES light, P0740 (TCC), and P0753 (Shift Solenoid A), and
last night, it wouldn't give up the key from the ignition switch, 'till I
disconn'ed the battery.

I've seen some post replys that say look at the ignition switch. Okay, but the key problem started LAST.

Another reply says K&N air filter oil might be fouling an intake sensor (MAF?). I put one in 6 weeks ago.

Where to start diags???

I don't get it, the 4x4 problem doesn't relate to the tranny issue.

I don't get it either - kinda' like good lovin' - of late...
But when I disconnected the battery sunday, the DTC's cleared, and everything functions perfectly.
This morning, the guages flashed again, so I'm about 100% positive that the ignition switch solenoid under the steering column is faulty. Another poster said that 'circuit 1020' gets shorted out by this fault, and can set several DTC's. Mine had two DTC's that he listed - P0740 (TCC (Transfer Case related?)), and P0753 (Shift Solenoid A(of tranny? or transfer case?)).
I'm guessin' the tranny malfunction and the X-case malfunction ARE related, if only by a common ECM circuit.
Chilton's does show the X-case, and the tranny range switch, AND the (blinking) instrument cluster on the same circuit, but there is no numerical designation - i.e. 1020.
Got any ideas about what the ignition switch solenoid is called, to search ebay?
Maybe I need an O2 sensor too???

It's just called an ignition switch. Did you get the Email I sent you? The attachment had part numbers.

10/4 on the email, podnah!
Had a bear of a time tryin' to get it to copy to file; I don't know what's wrong with my pc (or what's right with it...). I think it caught somethin' from the
ign. switch:-