Need some help on what to do next, here's the story so far.

1976 280z California edition (manf. date Sept.1975).

Bought the car in late Jan. 2019, car passed emissions test and it started and drove fine until 2 weeks ago when problem first occurred.

Engine runs very rough for about 1-3 minutes at high RPM when gas pedal is pressed, and exhaust kicks out white-ish / light gray fumes.

When gas pedal is released, engine dies, car will not idle.

Try to start again and engine cranks but will not start.

Let it sit for 1-2 hours and it will start again, same as above.

Makes me think it is flooded with gas and needs to sit before it will start again, but not sure.

Reviewed service records and saw that several basic maintenance has not been performed for a long time (anywhere from 2 years - fuel filter, to 8 years - spark plugs & air filter).

Here's what I have done so far:

Replace fuel filter.

Replace air filter.

Replace spark plugs.

Replaced fuel hose from tank to fuel pump (found it had a couple of gashes, but not dripping gas.... figured it should be replaced).

Replaced air regulator hose (appeared to be original equipment that was dried and appeared to have fresh crack in it).

Adjusted idle screw (tried 2 turns counter clockwise, no affect. tried 2 turns clockwise, no affect. set it back to original position.)

Did visual inspection of air and fuel hoses.

Tightened up all connections.

Inspected carbon canister, replaced under filter.

 

Anything I am overlooking?

Anything I left out in the problem description?

Any advice on what to test next?

I'm thinking maybe a bad/dying fuel pump.  They are easy to replace as they are mounted outside of the gas tank.

It could also be the fuel tank/screen- mine (and many others) was filled with rust/gunk that would clog up the lines and it would die.  

I took it to a radiator shop and had it boiled out, they also cut out the "screen".  No dying problems since.

He started another thread -