99 Ram 1500 Sport 5.9L vacuum leak. Only sucks air between like 1500 and 2500 RPMs at least that you can hear. I know the plenum is good just replaced it less then 1000 miles ago and no internal vacuum found. Just looking for a lil adivce as were to start past the plenum. Replaced the IAC cuz it was sucking air at idle. IAC fixed that, but still leaks when you get on it. Any ideas?