1985 245 DL Cold start after 6 years
 

Good afternoon fellow volvo peeps. My ide is still rough because I haven't had the time or money to do much. However, the car runs great for the most part. When I depress the brake pedal all the wqy while idling, the engine will die if I don't let up on the brake. If I don't depress it all the way to the floor it will keep running. As always all input and ideas are appreciated. I think I read something about this in a YouTube video about smoke testing for vacuum leaks. It also makes a high pitch squeal sometimes when the brake pedal is depressed. Again, thank you Volvonation.

It has to be vacuum related. The high pitch squeal is air escaping from the booster and it has to be a good size leak. Have someone else step on the brake while you listen/watch for a leak from that area. The smoke machine for leaks detection is expensive and not needed except for minor leaks that are hard to pinpoint...

Rough idle
 

You don't check the exhaust, you'd check the vacuum system by introducing the smoke in the intake manifold.