My 85 westy has a rough idle, which is worse when cold (backfires and
smells rich).

I've run most of the tests in the Bentley manual (page 24.20 : AFC
System check) with normal results.  But there were a few exceptions,
and I'd appreciate any advice you can offer:

(1) The Fuel Injectors all were about 17.5 ohms.  Bentley specifies
16-16.4.  Is this a problem?

(2) The Intake air sensor reads exactly 560 ohms at rest, however
when I move the sensor plate slowly and smoothy, the resistance jumps
around rather than increasing smoothly.  The carbon (?) potentiometer
wipe tracks are noticeably grooved and worn.

(3) At idle, the intake air sensor plate vibrates a bit.  If I hold
it steady, the idle smooths out.

(4) Bypassing the idle stabilizer results in a low idle and the engine dies.

Are these the symptoms of a bad AFM?

If so, how hard is it to replace myself?

Afterwards I'd need to take it to mechanic to do idle, timing &
emissions adjustments?

Thanks!