Not an erratic idle like a dirty throttle body gives you. That goes up and down when the AC compressor kicks on, and can send the idle down to 300-400 RPM and stall the engine out. Then it overshoots when the compressor cycles off.
death rattle. a sound produced by a person immediately preceding death, resulting from the passage of air through the mucus in the throat.
Hypernyms (rattle is a kind of...): tail (the posterior part of the body of a vertebrate especially when elongated and extending beyond the trunk or main part of the body). Holonyms (rattle is a part of...): rattler; rattlesnake (pit viper with horny segments at the end of the tail that rattle when shaken).