Cruise control on the road nor idling replace all sensors steel no go

cruise controls are controlled by the following switches and sensors
1 the switch itself
2-- the clutch pedal sensor or the VSS in the auto transmission
3 the brake sensor ---4-- the gear change switch or selector
5-- the engine speed sensor ( tacho)
6-- the road speed (VSS )
if 1 or a combination is not working or is outside parameters , the cruise control will not switch on
the road speed in a manual is set at around 20 mph and any less will not engage cruise control(CC)
changing gears in a manual will disengage CC
touching the clutch pedal will not allow engagement or will disengage CC
for some sensors run the fault codes

cruise controls are dependent on the following sensors all working together
brake sensor
clutch sensor
auto--vehicle speed sensor
rpm's sensor
fuse for the cruise control
cruise control switch either or all not working will stop the cruise control from engaging
road speed at which you can engage the cruise control has to be above a reset speed before it will cut in and work

cruise controls are controlled by several units
VSS or road speed sensor, clutch and brake sensors , engine speed (tacho) and the on/off switch
cruise controls will disengage automatically if the road speed is too slow ( higher for manuals than autos ) so if the road speed is below around 20mph it may not engage at all as the VSS says it is too slow for the engine rpms
check all sensors for adjustment

cruise controls need all of the following sensors to be in line to work
VSS sensor (road speed 0
tacho (engine rpms)
brake pedal sensor
clutch pedal sensor
power to the unit (fuses)
any one unit not performing will stop the cruise control from working

run the fault codes
cruise control needs the following to work together as one or more will stop it from working.
VSS sensor, (road speed /speedo)
engine rpms/tacho
brake switch sensor/
clutch switch sensor
cruise control switch

not being informed if it is auto or manual, here are some of the items that control the cruise control
brake pedal sensor ,
clutch pedal sensor,
vehicle speed sensor
engine ignition control module , tacho ,
vehicle speed --will disconnect if the road speed is below setting minimum speed
ratio changing
bad cruise control switch
wiring and connections
ecm problems
problem cruise control module

cruise control operation is reliant on the following
road speed sensor ( speedo or VSS sensor )
engine rpms tacho/ ignition coil/module problem
clutch pedal sensor (VSS in automatic )
gear selection position sensor ( not properly adjusted causing flickering of the selector light)
brake pedal sensor
bad ground wire connections
r all need to work together or the CC will stop working
nothing to do with vents and all that you mentioned.
wire connections and harness connections for the transmission are suspect
CC will not operate under certain engine rpms and road speed

Idle Air Control Valve Pintle may be bad If you disconnect the IAC and the problem ceases it can point to this being the problem.: Removal & Installation 3.5L Engine To Remove:

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Remove the fuel injector sight shield.
3. Drain the cooling system.
4. Remove or disconnect the following:
   • The air cleaner intake duct. Figure of IAC and TPS electrical connectors disconnected.
     
     
   • The idle air control (IAC) valve and throttle position (TP) sensor electrical connectors. Figure of cruise control and throttle control cables removed from throttle lever.
     
     
   • The cruise control cable and throttle control cable from the throttle body lever.
   • The fuel pressure regulator vacuum hose, positive crankcase ventilation (PCV) hose and the throttle body vacuum port hose.
   • The throttle body coolant hoses.
   • The throttle control cable bracket, leaving the throttle and cruise cables connected.
   • The upper nut holding the throttle body to the intake manifold.
   • The throttle body assembly.
5. Clean the gasket mating surfaces.

To Install:

1. Install a new gasket and new studs if necessary.
2. Install or connect the following:
   • The throttle body assembly.
   • Start the top nut by hand.
   • The throttle body coolant hoses.
   • Position the throttle control cable bracket and hand start the retaining nuts and bolt.
   • Torque the three throttle body retaining nuts to 89 in.lbs. (10 Nm). And the bracket retaining bolt to 115 in.lbs. (13 Nm).
   • The throttle body vacuum port hose, PCV valve hose and the fuel pressure regulator hose.
   • The throttle control and cruise control cables to the throttle body lever.
   • The IAC valve and TP sensor electrical connectors.
   • The air intake duct.
3. Refill the cooling system.
4. Install the fuel injector sight shield.

4.0L Engine To Remove:

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Relieve the fuel system pressure.
3. Remove or disconnect the following:
   • Negative battery cable.
   • The Mass Air Flow (MAF) sensor electrical connector.
   • The air cleaner intake duct.
   • The PCV valve fresh air tube. Figure of cruise control cable removed from throttle cable bracket.
     
     
   • The cruise control cable and throttle control cable from the bracket.
   • The cruise control cable and throttle control cable from throttle body lever. Figure of IAC valve and TPS connectors removed.
     
     
   • The idle air control (IAC) valve and throttle position (TP) sensor electrical connectors. Figure of fuel lines removed from retainer on throttle cable bracket.
     
     
   • The fuel feed and return lines from the retainer on the throttle control cable bracket.
   • The transaxle shift cable clip from the throttle control cable bracket. Figure of throttle body removed from water crossover.
     
     
   • The throttle body from the water crossover.

To Install:
NOTE: The Mass Air Flow (MAF) sensor inlet and the outlet of the air cleaner assembly must line up when installed. Misalignment may cause MIL illumination or driveability concerns.

1. Install or connect the following.
   • The throttle body to the water crossover. Torque the bolts to 106 in.lbs. (12 Nm).
   • The IAC valve and TP sensor electrical connectors.
   • The throttle and cruise control cables to the throttle body lever.
   • The throttle and cruise control cables to the throttle control cable bracket. The transaxle shift cable clip to the throttle control cable bracket.
   • The fuel feed and return line retainer to the throttle control cable bracket.
   • The MAF sensor electrical connector.
   • The air cleaner intake duct clamp. Torque the clamp to 27 in.lbs. (3Nm).
   • The PCV valve fresh air tube.
   • The fuel injector sight shield. Torque the nuts to 20 in.lbs. (2.3 Nm).
2. Install the negative battery cable.
3. Pressurize the fuel system and verify no leaks.

IT SOUNDS LIKE A PROBLEM IN THE ACCUATOR MIGHT NEED ADJUSTMENT OR PROBLEM IN THAT CIRCUT

My Durango did the same exact thing. It would seem it was shifting from o/d to third constantly while driving down the road. As it turns out, it was the throttle position sensor. This may or may not solve your problem, but is a good place to start.