generally it isn't really coming from the intake rather it is echoing from the engine through components into the intake.
the intake is hollow so it echoes most sounds making it seem noises come from the intake when most of the time it's not the part making noise.
check your oil level.
if you have OHC's that could be a next place to check
If its a legitimate knocking then you would want to go with head gasket if its a tapping you would be looking at a valve
My 2000 Grand Prix would have a low-speed knocking noise coming from the drivers side as the CV axle was failing. The loss of lubrication in the CV Boots allows the joint to make a knocking/tapping sound at a low speed. If the knocking is coming from the engine compartment, then it could be an entirely different problem.
Check your oil level.
hey man i got a 2000 mercury cougar v6 it is makeing a tapping noise under my manifold, and i dont know what that could be. but it sounds like you might be haveing the same problem im haveing. suggestion: try checking where that tapping noise was again, it might be under your manifold!.
I'd check the exhaust manifold first. A cracked manifold or leaking gasket can cause a sound that's a lot like what you describe.
I get knocking & ping noise coming from the fuel injectors
Is this coming from the engine? If it is it sounds like you might have some lifter problems. Or the worse part is if you have a rod knocking. Intrepids did have some egine problems.
if it sounds like the knocking is coming from the bottom of the engine i would bet it was the rods or rod bearings may be worn. if the knocking is on the top ,then i would have the lifters and or the rocker arms checked.
possibly low oil or low oil pressure, the tapping may be coming from the oil operated hydraulic lifters.
A other small child
Check the water pump. Examine it for traces of dried coolant that might be leaking out of the casting.
there is a center in your intake manifold #29221-39600 that has 6 samll flaps and 2 screws per flap they have been known to fall out and boucne around in the cylinder!!