Ford e250 van running very poorly. Left engine bank has a place for two vacuum lines to be connected. Only one is present. Should there be two or just a plug on the open metal connection. Where do they go?

https://www.google.com/search?q=1992+Ford+E-150%2C+with+5.0+engine+vacuum+line+diagram

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If your 96 E250 300ci was running perfectly and then started missing and the code is indicating a miss fire in cylinders 1 and 2, there could be a few potential causes. Here are a few steps you can try to troubleshoot and resolve the issue:

1. Check the ignition system: Make sure that the ignition system is functioning properly. Check the distributor cap, rotor, spark plug wires, and ignition coil for any signs of wear or damage.
2. Check the fuel system: Make sure that the fuel system is functioning properly. Check the fuel filter, fuel pressure, and fuel injectors for any signs of wear or damage.
3. Check the compression: A compression test can help to determine if the engine is getting enough compression to run properly. Low compression in cylinders 1 and 2 can cause the engine to miss fire.
4. Check the vacuum lines: Make sure that the vacuum lines are properly connected and not leaking. Any vacuum leaks can cause the engine to run poorly and miss fire.
5. Check the PCV valve: The PCV (positive crankcase ventilation) valve can become clogged or malfunctioning and cause the engine to run poorly and miss fire.
6. Check the EGR valve: The EGR (exhaust gas recirculation) valve can become clogged or malfunctioning and cause the engine to run poorly and miss fire.
7. Check the Engine Control Module: The Engine Control Module (ECM) controls the ignition and fuel systems and if it's malfunctioning it can cause the engine to miss fire.

It's important to note that some of these steps may require special tools and knowledge of the vehicle's engine system, so it's best to take it to a professional mechanic to avoid causing more damage.

Patrick I think you will find about any vacuum line that is broken, cracked or leaking that is hooked to the engine will make it run bad. It sucks more air that is needed to run smoothly. Please re state your question more completely if possible? Explain exactly the problem your having.

Codes indicate; Both sides of the Engine are running lean. Your fuel pressure reading indicates; Fuel pressure is way too low should be about 48 pounds Min to Run correctly!

Check voltages for 13.8-14.5 Volts at the battery while running and about 12 volts+ at the Fuel Pump Fuse, Check for fuel line leaks starting from fuel tank (Most likely won't find any), Next should Replace the fuel filter in this case regardless of what you find (Check for leaks before and after replacement), Next Replace the fuel regulator (Check for Fuel and Vacuum leaks) and finally Replace fuel pump.

However, other opinion are as follows;
What causes the P2197 code? O2 sensors create a rapidly oscillating voltage signal based on the amount of oxygen in the exhaust stream. The voltage signal ranges from 0.1 volts to 0.9 volts. This oscillating voltage takes place in a matter of milliseconds and should never maintain a constant voltage. This code states that the voltage is not oscillating and is being held high indicating a lean condition in bank 2.

P2195
Possible causes Faulty Front Heated Oxygen Sensor Bank 1 Front Heated Oxygen Sensor Bank 1 harness is open or shorted Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection Inappropriate fuel pressure Faulty fuel injectors Intake air leaks may be faulty Vacuums leaks

Read more: https://www.autocodes.com/p2195_ford.html

It'll work ...Enjoy!

One line supplies vacuum from the intake manifold to the control panel. The other line runs back from the control panel to the heater water control valve, which is along the heater hose. The vacuum port on the valve is at the top of the cylindrical actuator.

Is the van running rough at idle? Does it seems to have a slight miss as you accel? What kind of mileage do you have. Ford 4.2L with high mileage could have EGR ports that are clogged in the lower intake. Unplug the EGR vacuum line and see if the misfire goes away ( 303 is a cylinder #3 misfire code )

The vac tank is usually in the engine compartment, don't know about a check valve for the a/c unless you are talking about the HVAC control on the dash.

those two codes are for the o2 sensors. both are the upstream sensors on the front and rear banks. so they are desinagted bank 1 sensor 1 and bank 2 sensor 1. them most common cause for this is faulty o2sensors , bad gas and of a poor running engine. so if your car runs good (no misfire) and gas is ok then replace the o2sensor witch is the very most common cause.

One of your deflector door servos or the door itself, is hanging up. To determine this more clearly, run your vehicle for about two minutes and shut down the engine. Move your function selector knob from defrost to floor to panel and listen carefully for a sweeeping sound. if you do not hear this sound you've got to check under the dash for a loose vacuum line or under the hood for a loose or broken line to the vacuum accumulator. The vacuum accumulator is a large black ball on the firewall with only two lines connected to it. One line is about3/32nds of an inch and the other will be about one quarter inch. Check these lines well, for they control ALL the functions within yout climate control. Best of luck my friend, Dana

usually the check valve is in the engine compartment. look on the pass side at the heater box and see if the vac lines have a check valve in it it should be a grey or black line