1998 voyager idle mystery

I have a 1998 grand voyager 3.0 with an idle prob. The engine runs fine at higher rpms but at idle it pulses. No detected vac leaks in fact it has to much vac. Remove a vac hose and it seems to smooth out.My mech buddy and his high tech friend thought that it was mech. oriented.The theory there was that one of the cam pully pins was pulled out of place.Causing a timing prob. So I stipped the engine down to that point and as I expected it was not the prob. T belt is new..all teath Ok. PVC cleaned but not replaced. Idle air senc.
cleaned.??? Iput in a new distib. wires,plugs.??