Cindimccs

When my 88 Legend is in drive, it makes a terrible noise, like a sick foghorn. This only happens when the car is in drive and actually moving. It happens immediately on taking off from a light and then again every few seconds. It sounds like it is coming from underneath the housing for the air cleaner. Could this be something to do with the amount of air going into the intake manifold? I have replaced the air cleaner and the air intake duct so far, but still have a problem. Any ideas? Also, the car has a very high idle when in drive. If it's in neutral, it will kick itself down to a normal idle, same with park and reverse, but in drive, it just wants to lunge forward the idle is so high.