I currently own a 1985 Nissan 720 4x4 King Cab with the Z24 engine on it. The Idling and Stalling problems began a couple of years ago. BTW Here's a pic of what the engine looks like (Not mines personally but you get the gist).
So here's what I have done so far in trying to fix the issue
1. New Water Pump
2. New Fuel Lines cause they ripped
3. New Distributor Cap and Rotor
4. New Spark Plugs
5. New PCV Valve
6. Did the smoke test and the only places where smoke comes out is the bpt valve, the weep holes on the vacuum switches and out the top of the carburetor.
7. New Radiator Cap
8. New Anti-Dieseling Solenoid
9. Fixed 2 electrical shorts thanks to the multi meter measuring on the fuse box
10. Replaced a corroded terminal on the ecc main relay and at the same time got the anti-dieseling solenoid and the rest of the engine to receive battery voltage.
11. Manually testing the EGR and BPT valves and they both work fine.
12. Found out that the oil pressure sending unit for some reason became unplugged so plugged that back in
And after ALL THAT, the problem still occurs. However recently, I've been doing some tests and here's what happened.
1. Plugged the vacuum hoses to both the tvv valve and the vacuum control valve and problem doesn't go away
2. Hooked a vacuum gauge to one of the hoses and it reads steadily around 5-8 inhg at idle.
3. Hooked it up to one of the hoses that goes to the manifold and reads the same thing. It should read around 17-22 Inhg.
I don't know what's going on here. I don't know how many people on here have experience with working on cars but I need help and I don't wanna spend a lot of money and my time working with this thing.
PS: My dad got it in late 1985, rebuilt the top end of the engine little over 20 years ago before I was born and at that point it had 190,000 miles on it. Now it has little over 243,000 miles on it.