Just bought a 95 z 28 its all ready had k&n cold air intake, phantom air to fuel ratio, and vacuum gauges and a port to plug a lap top into so i was told, the air to fuel ratio gauge is showin its running to lean and running ruff sometimes it will jump all the way to rich. one extreme to another

Unlikely fuel filter.

Intake air leak is a possibility; perished vacuum hose, pcv valve, brake booster...

Might be the air/fuel ratio. If nothing else is found to be faulty it would be a good idea to have the injector spray patterns checked.

Slight defects of the intake valve seats can also affect the air/fuel ratio at low speed. A cylinder leakage test would discover that.

P1800 is the VIAS system. Most likely the intake runner control vacuum actuator is defective. Where did you get the ABS info?
P1273 NISSAN - Air Fuel Ratio Sensor 1 Bank 1 Lean Shift Monitoring.
Possible causes - Faulty Air fuel ratio (A/F) Sensor 1 Bank 1
-Intake manifold or vacuum hose leaking (check this first)
- Air fuel ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
- Air fuel ratio (A/F) Sensor 1 Bank 1 circuit poor electrical connection
- Fuel pressure
- Faulty Fuel injector
- Faulty Air Flow Meter
If all seems ok then replace the cylinder bank number one O2 sensor and the bank two sensor, replacing only one sensor can lead to another check engine light. These are the sensors before the catalytic converter.

Yeah, about ten times better. Look, you need vacuum in the intake manifold, you have to have it or air wouldn't rush in from the air cleaner, the engine would not breathe, and it would sit there and barely run, or not run at all.
By design, vacuum is created when the piston in a cylinder is pulled down by the crankshaft and the intake valve is open. So air from the intake moves into the cylinder, leaving a vacuum (lower air pressure) in the intake manifold. For more air to be drawn in, but it's a set amount of air. Vacuum leaks and leaking intake manifold gaskets pull in extra air and lean out the air/fuel mixture too much. So plug off that hole and make sure no vacuum leaks.
For your '72, an inexpensive vacuum gauge would be a wise investment. Check this site for its usefulness:
http://www.secondchancegarage.com/public/186.cfm

All engines run with a vacuum in the intake, a good engine should have a steady vacuum of between17 and 21 inches on the gauge at idle. The tighter and less worn the engine is, the vacuum will be higher, like 21 inches Hg. But should be at least 16 or 17, and steady. Learn how to use a vacuum gauge and you can tell a lot about the engine's condition-just check the site.

If you have a code for a miss on one cylinder, it could be the fuel injector instead of the ignition. It could also be a stuck or burnt valve problem.

intake manifoold leak check all vacuum lines replace all vacuum lines if look cracked ,spark plugs could be fouled out by leaking fuel injectors, clean fuel injectors,replace fuel filter,replace air filter,replace spark plugs and wires,do tune up see if it helps if not.could have leaking intake manifold gasket or leaking egr valve,use engine vacuum gauge check engine vacuum for intake manifold gasket leaks.

The first thing to have checked is the fuel pressure, low pressure kills the power.

Hi, I recommend you check the fuel pressure regulator for a torn diaphram. The vacuum reduces fuel pressure when the engine is not in high fuel demand. However, since the intake manifold is the source of vacuum for these type regulators, when the diaphram tears, it allows fuel to be sucked through the regulator directly into the intake manifold, thus causing a rich fuel/air ratio. To check a regulator on the rail, pull the vacuum hose off the regulator and plug the hose with a golf tee. Start the engine and watch for fuel to come out of the regulator vacuum port. If fuel comes out, replace the regulator. A diagram showing your regulator is pasted in below. If this is not the problem, please get back to me.

Lean running condition A lean running condition means that the air/fuel mixture is unbalanced, and that the engine is getting either too much air, not enough fuel, or a combination of both. Optimally, this ratio should be around 14.7 parts air to 1 part fuel by mass, at low or cruising loads. This ratio is known as stoichiometric for gasoline. Ideally, at WOT, you should aim between 11.5:1 (Rich best torque at WOT) and 13.3:1 (Lean best torque at WOT).
Running lean, like having your spark timing too advanced, creates much more heat during the combustion process. This can lead to piston seizure, a hole in the piston, melted spark plug electrode or other complications due to overheating. You will not be producing peak power, and your exhaust will also emit more oxides of nitrogen, arguably one of the worst byproducts of gasoline combustion for our environment.
Common causes of a lean running condition are an improperly tuned carburetor, clogged fuel line, clogged fuel filter, or a vacuum leak.
Preforming a plug chop is a good way to find out if your engine is running too lean, as you will see a powdery white residue on your spark plug in the presence of a lean condition.
On the other end of the spectrum, richer ratios will also cause lost power, however this will most likely be accompanied by black smoke (around the 9:1 fuel/air ratio area), and fouled spark plugs.

With a good air filter, and a good fuel filter you shouldn't really have any problems since the fuel pump is good. You could have a vacuum leak, this can be identified by using a can of carb. cleaner with the tube attached so that you can spray near & around your vacuum hoses & connections. If you spray near a leaking hose, or a cap, or connection that is leaking, the engine will slow or stall. Only spray a second or two & allow the engine compartment to air out between spraying as it is a flamable product.

Short of that, you could be looking at ta idle speed control motor/throttle position sensor.

Testing the vehicle with a vacuum gauge could assist in identifying any other issues such as exhaust or valves. Gauges usually come with instructions & just need to be hooked to an available intake port.

good luck.