Exactly what you would expect from a vacuum leak. While you're under the hood replacing the hose (or hoses - chances are they're all of the same vintage as the one that failed) check the bellows hose from the AMM to the throttle body. Over time, the bellows weaken and collapse, especially if they have blowby oil contamination, and that restricts the air intake, and can cause the same symptom.

Last year, my daughter's 89 740 couldn't get over 2000 RPM, and was stalling at stops. I found a small crack in a vacuum hose and a major bend in the bellows. After replacements, I took it out to the interstate, and went from 0 to 90 without a miss.

If you hear the hissing and it runs rough when you push on the brake peddle then the brake booster diaphram is probably bad. Also check for a loose or split intake hose. Usually a small vacuum line leak woun't cause that big a problem.