Nissan Repair: 1986 .5 nissan d21 pickup, nissan d21, factory airbox

Question
I recently bought this for my son. Runs and drives really well and automatic transmission shifts normal. It has 160,000 miles. Its missing some kind of airbox that should be connected to the breather. My problem is the idle speed is way to high when its in park and the fuel mileage is only 19 mpg. I have backed the idle adjuster screw all the way out and it didnt drop at all. I partially covered the opening on breather with my hand and it helped alot but it really pulls a lot of suction. Also when the accelerator is pressed hard it stalls and wont pick back up until you let off the gas. Any ideas? Thanks.

Answer
William,

The factory airbox would be the answer here as I am sure the crankcase bypass hose is open to the atmosphere.  That would account for the high idle.  I would go to a wrecking yard and get one and install it.  Or, find the hose, something like a inch in diameter and get a connector and connect it to the intake air hose so the computer will be able to meter the air.  Either way should connect the problem.