Vacuum leak in Ford Taurus

There's a sticker under the hood that shows the vacuum hose routing. If you can hear the hiss inside the car, check the operation of the vacuum controls for the heater / defroster.

This guide can help

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Spray a little water on the engine when it's still cold and running. You will see and hear it get sucked into a vacuum leak. This works well for intake manifold gaskets but spray the vacuum hoses too. You can also pinch the vacuum hoses where they originate on the engine. If one affects engine operation, follow that hose to its branches and follow each one.

These cars had a problem with the IAC motor making a noise and making the car jump etc.

Here is a guide to show you what you are in for when changing the motor out.

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

Here is what it is like for your car

Follow removal procedure in reverse order. Tighten the idle air control valve retaining bolts to 8-12 N.m (71-106 Lb-In)

Check out the diagrams (Below)

Please let us know what happens.

Cheers, Ken

Code p0442 is an indicates a fuel vapor leak in the EVAP control system.
It means a very small leak has been detected. In fact, the leak can be from a very small hole as small as 0.04" in diameter.

The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage.

1st check and or replace gas cap clear codes

2nd if code have to have a smoke test the system

as for the idle
check IAC valve remove and clean

if have vacuum leaks I would expect to see codes like p0171 and or p0174

DTCs P1131 and P1151 indicate air/fuel ratio is correcting rich for an overly lean condition. DTCs P1132 and P1152 indicate air/fuel ratio is correcting lean for an overly rich condition. DTCs P1130 and P1150 indicate fuel system has reached maximum compensation and HO2S is not switching at the adaptive limits. Possible causes are:
Fuel system malfunction.
EGR system malfunction.
Air intake or vacuum system leak.
Engine oil level too high.
Incorrect cam timing.
Restricted air cleaner.
Faulty PCV system.
Excessive internal engine wear.

Vacuum leak, very possible
check PCV valve hose