Engine running weird

Hi! 

I have an issue with my 1988 caddy 1.8L
It alternates between a really low idle (to the point of it staling unless I slightly press on the throttle) and have a quite high idle. 
I haven't been able to discern a pattern to when it" switches state" sometimes it can spend 30 min or more before it switches and sometimes only a couple of minutes but generally I feel it tends to idle hight most of the time. 

I'm quite new to mk1s so please excuse me if I'm missing something obvious.

Cheers
/TAb

Is it the carb engine with the OE Pierburg carb?

If so the carb can give all sorts of trouble with its vac lines , mounting base and auto choke.

jazzydog said

Is it the carb engine with the OE Pierburg carb?

If so the carb can give all sorts of trouble with its vac lines , mounting base and auto choke.

No, it has K-jet injection. 

I think I would start by researching the WUR (warm up regulator) and the cold start / 5th injector (I think it's called).