The engine running too cold may be a faulty thermostat not regulating the engine temperature and I would try that first. Here are directions to replace the thermostat, temperature sensor and crank sensor (the crankshaft relearn needs to be performed at a dealership as the Tech 2 scan tool needs to be used).
Important: When replacing the CKP sensor with a new sensor or reinstalling the original sensor, use the following recommended procedures:
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Tighten the bolt to 9 N·m (80 lb in)
Notice: Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.
Notice: Replacement components must be the correct part number for the application. Components requiring the use of the thread locking compound, lubricants, corrosion inhibitors, or sealants are identified in the service procedure. Some replacement components may come with these coatings already applied. Do not use these coatings on components unless specified. These coatings can affect the final torque, which may affect the operation of the component. Use the correct torque specification when installing components in order to avoid damage.
Tighten the sensor to 20 N·m (15 lb ft).
J 38185 Hose Clamp Pliers
Important: The water inlet housing (2) and the thermostat are replaced as an assembly.
Tighten Tighten the bolts to 9 N·m (80 lb in).