Navara running issues, won't idle, surges at low revs

[estate_]

Pretty much as it says in the title. Had my 86 D21 Navara break down on my the other day on the side of the motorway, it just lost spark due to a snapped points spring. Anyway got it towed home, put some new points in it, it started right up and idled fine with the odd drop in revs, but would idle fine and be sweet up to about 3.5k rpm, where the rev counter would bounce all over the show and it would sort of bog down. Anyway I realized i hadn't cleaned or gapped the points properly, so did that, points gap at .020(spec is .018-.022)

It will now run fine at higher revs, but will not idle, and surges and hunts at anything below 1500rpm. I picked up a new dizzy cap, condenser, coil etc as they were probably due based on the state of them and the points, so did those. Still no luck.

So not too sure where to go from here, the issue it currently has, seems like it would be carb related to me? But it seems a bit odd that the carb would just happen to play up at the same time as it was off the road for the points issue. The carb has always had an issue where the float wasn't adjusted right, so the fuel level in the bowl was below the mark it was meant to be at. But it seems a bit odd that it would play up now, at the same time as the points? I adjusted the float in the carb and now it sits at the right level, but still having the issues at low rpm.

It is a Nissan Navara 1986 with the Z18S carbie engine. If anyone has any suggestions as to what to try from here then that would be great. The carb has always been a bit suspect, as above with the float issue, and the previous owner disabled the choke and seems to have done some dodgy shit to it.

Cheers

[smokin' joe]

vaccum lines need sorting

[Jase]

take a video of it running and chuck it on Youtube,

surging is normally vacuum leak which you can find by squirting carb cleaner etc around whilst its running,

if it ate the points check the dizzy shaft has no play in it, as they tend to shag points caps and rotors real quick once they start walking around

[estate_]

It has now started idling fine for no apparent reason, but at ~1500 rpm, it used to idle at ~700rpm cold, ~900 warm. But this also seems to be pointing to a vacuum leak then? Will go see if i can find it now, cheers for the advice

[estate_]

As above, it now idles at 1500rpm with ever so slight surging, so i wound back the idle screw to see how it behaved at lower revs, it will still not idle much below 1500rpm without big surges and stalling. Disconnected the vacuum line from the carb to the dizzy, changed the idle slightly and there was a noticeable vacuum if i put my thumb over the line coming from the carb. Sprayed a few areas with start ya bastard and couldn't find anywhere that would obviously pick up revs, but will go have another try now.

Here is a video of it, in the whole video I did not touch the throttle, just the idle screw when you see my adjust it. As you can see at 1500rpm its not very noticeable, and hardly an issue, but lower than 1500 doesn't idle well

Oh and sorry about the video being on an angle