Slow down/stop car stalls?

[Itzav6]

When at idle the car is fine. When I Shift into gear feel like it's going to stall but doesn't. Drives fine but when I press the brake to slow down it stalls. Turn the key starts back up perfectly fine. What can the issue be?

 

[Steve V]

What are your IAC counts on the scanmaster?

 

[Itzav6]

What are your IAC counts on the scanmaster?

I fixed the stalling issue. Today I got it up to 75mph but when it got there I sound like the rpms was to high. Like if it was an high idle while doing 75?

 

[Steve V]

Trans slipping?

 

[Itzav6]

Trans slipping?

Hope not car only has 69k miles