when traveling at speeds over 25-30 mph, i get a whining/whistling noise whenever i let off the accelerator. as soon as i barely apply pressure to the gas pedal the noise goes away. (as far as i can tell since the road/engine noise is so loud). it does it every time until i get below 30 mph. i even coast from 40 mph to 30 mph and listen as the noise grows fainter and fainter as i near 30 mph. i can't get the noise to reproduce itself in the driveway, it only does it when traveling. i have tried spraying carb cleaner around the carb. while running at different rpm's in the garage, but can't find any gasket leaks. some help would be nice. 350 sb......rochester carb.....th350 trans......goofy driver with nagging wife.