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.
Medical Definition of trembles. : severe poisoning of livestock and especially cattle by a toxic alcohol present in a snakeroot (Eupatorium rugosum) and several rayless goldenrods (especially Haplopappus heterophyllus) that is characterized by muscular tremors, weakness, and constipation.