hey everyone i have a 99 gmc sonoma with the 4.3 v6 vortec engine and my problem is that when im driving there is a "whistle" sound coming from the engine whenever i have my foot on the gas as soon as i let off it stops and it's annoying as &^%* when driving. i was told this was caused by my throttle body spacer but i also was told this could also be a vacuum leak. has anyone came across this problem before????? thanks in advance!!!!