Should be on top of manifold/engine. See below- this is what it looks like, has 2 bolts to hold it on and a plug connector. Do not start engine with it off, extra air could cause over revving,.
99 Durango doesn't have a Heater Control Valve, It only has a thermostat
A Dodge Durango does not have a water control valve in the heater plumbing. The cabin temperature is controlled with airflow control doors.
There isn't a water control valve.
The 2004 Dodge Durango EGR valve can be found on the firewall in the engine compartment. The EGR valve will be on the passenger side of the firewall.
The IAC valve is located in the intake manifold
the contol valve is in the housing the input shaft is connected to the valve
Inside the transmission, on the valve body.
The PCV valve is located in the valve cover, on the 4.7L it is in the side of the oil filler housing.
Throttle body
It is located on the firewall above the back of the valve cover on the driver's side of the engine. It is mounted with a rubber and slides up and off the mounting bracket.
On a 2000 Durango V8 the PCV is located on the side of the oil fill tube under the cap
Front passenger corner of the engine.