Hi Idle on diesel

Greetings!

Got a (small) problem with my '96 1.2 diesel van.
The head gasket went so out came the engine and off came the head.
The gasket had blown on no 4 (not belt end) and the cylinder sealing ring was the cause.
Head was checked for flat and ok, so all cleaned up and put back together.
Finnaly got it bled and started and runs ok.
But it idles fast, about 1200-1300 rpm- hot or cold.
I didn't remove the injectors- just the rocker assembly. all components were kept in cylinder order so no mixing up.
i adjusted the idle screw, which lowered the idle, but when i rev it and it comes down to settle it cuts out.
the lowest point that i can get it where it does not cut out it seems to stutter and then come back.
I read a post on here about how to adjust the timing on the injectors (cant find it now!) and have tried both ways half a turn at a time but this doesn't help.
If i retard the timing then it smokes but does idle lower, so advance it slightly and the smoking stops but the hi idle comes back.

I know the belt timing is ok.
the throttle cable is not sticking as it does it with the cable disconnected.
Kinda pulling my hair out now.

I would be so gratefull if anyone has any ideas on what this could be.
Thanks
in advance
Brad

I don't know the diesel stuff.

But does it have some form of coolant feed to control the idle between hot and cold?

thanks for the reply
not that i can see

Don't suppose the timing belt is on a tooth out somewhere?