Land Rover Repair: 1995 Discovery - Stalls , idle rmp varies, chk engine light came on, vacuum hoses, oxygen sensor

Question
1995 Discovery 5 speed standard.
I recently replaced the starter after trouble shooting a not turning over problem.  Then my
wife complained it would stall when rolling
to a stop.  I tried it and after it warms up,
the rpm is around 400 then sometimes, it is
around 800. When it is around 400 and roams,
this is the usual time it stalls.  I replaced
the T from the crans case vent to the intake.
The check engine light came on and stepping
the codes backwards, would only show 44.
This relates to the left oxygen sensor?
Since I cleared the code by removing the
battery connection, no other check engine
events have been captured. I have been using
low 87 octane fuel.  Oil was very dirty last
change.  Some minor valve noise is heard ( tic ).
History - Vacume advance diaphram replaced
about a year a go.
Recent plugs, wires, cap, rotor.

Regards,
Art Wilcox  

Answer
You could have a tune up problem - it may be missing or skipping.

You might have a problem with the idle control circuit.

You might have damaged vacuum hoses, or the breather may be open to the air or plugged

All those things could cause your symptom