Stalls at idle?

There could be may reasons for this condition. If your check engine light is "on", please have the codes read and post them here so that I can help your track down the problem.

A few things to check/complete:

Check for loose/disconnected hos going to the air cleaner housing. If a major hose is disconnected or loose it could cause stalling.

This guide will help

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Clean the throttle body, often when dirty, these can cause the engine to stall.

Check for major vacuum leaks such as a large vacuum hose disconnected from the intake manifold or throttle body. Be sure to check the PCV hose (check its entire length).

Check for loose connections at the positive battery cable, where it attaches to the under hood fuse box. Also at the negative battery cable where it connects to the engine.

I'm not sure I follow exactly what you're doing, but it sounds like the engine will run if you introduce extra air. If that sounds right, the problem might be due to having the battery disconnected during the head service. Disconnecting the battery will cause the Engine Computer to lose its memory. It will have to relearn minimum throttle before it knows when to be in charge of idle speed.

To meet the conditions for the relearn procedure to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the brake or gas pedals.

Caradiodoc

Have you tried removing the negative battery cable for about a min booking it back up and see how it idles?Does it idle too high or too low?

Check for vacuum leaks at the engine. Also, check fuel pump pressure. The most common cause of this type of problem is a bad idle air control valve (IAC). It is located on the throttle body.

Have you checked for codes in the computer yet? If you turn on the ac if the ac works does the idle increase?

Have you tried lightly taping on the idle air control motor to see if the idle goes up?There really is no trouble tree for what happened with replacing the battery.

You don't. It's automatic and set by the Engine Computer through the automatic idle speed motor.

If the battery was recently disconnected or run dead, the computer will have to relearn "minimum throttle" before it will know when it must be in control of idle speed. To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the brake or gas pedals.

Caradiodoc

Its possible but I don't know why that would fail when you changed the battery. You said it started the idle issue as soon as you changed the battery.