Hi all,
My '81 B23E after sitting for a week or so ( I don't use it all that much ) has taken to only running on 3 cylinders. Generally speaking it is use once a week, but sometimes might sit for a couple of weeks. However, when needed it needs to run right.

Prior to this condition, when starting from cold, the engine runs ( in park or neutral ) at only approx. 700rpm. This is in an Aussie temperate climate average of 50 defrees f.

Being a B23E it is fitted with the K Jetronic fuel system. It's a low mileage ( 112,000 kilometres or 70,000 miles ) car.

Running on 3 cylinders, it's a pig for sure, won't go up hills etc.
( once in the past, with this same symptom, cleaning one of the injectors fixed this condition, but not the slow idle on start up).

Tried cleaning out the injectors and testing fro leaks at the injector, but no go.

Can anyone please suggest a modus operandi for curing both these ills ?
Haynes manual is next to useless in this circumstance. I'm unable to afford to take the car to a dealer who charges some $85 per hour.
Thanks in advance.