Speedometer does not work correctly all the time. Cold weather seems to make it go hay wire. Never stays stuck when the engine is off but registers 15 to 50 mph faster than actual speed

Test engine coolant temperature sensor not registering a cold engine. this is a two wire sensor with a wire retainer holding connector on.

Could be the speedometer, or the speed sensor in the transmission.
Is the check engine light staying on ?
If it is, you should have the computer scanned for trouble codes. You may find a code for the sensor.

the VSS and TCM control your problem
could be wiring failure or harness connections near the transmission

The issue you describe seems to point to an "Electrical Effect" Most often (in my experience), the CAUSE is seldom discovered and the owner simply lives with it. However, during cold weather, numerous electronic components behave differently (sensors, wiring, connectors & wiring connections, etc.) Was there ever a "Check Engine" light/warning when this happened? If so, find an OBDII (On-Board Diagnostics II) scanner and see what/which code(s) were set/stored in the ECU (Engine Control Unit). If any, this could help you narrow your search/diagnostics time to possibly find the CAUSE. Often/frequently I have found that poor/loose/questionable ground circuits CAUSE a great deal of these kinds of problems (as connections/contacts expand in warm weather (getting larger and tighter) and in cold weather 'shrink' (getting smaller and looser). Best I can offer without actually putting my hands on the vehicle. There are literally dozens of 'GROUND' circuits in a vehicle -- your description points to ESC and Engine RPM -- that's were I'd start. You'll want to get your hands on electrical wiring diagrams/schematics of your vehicle. You can go to WWW.HMASERVICE.COM and register your vehicle (by VIN #). Afterward, you'll have access to shop manuals, Technical Service Bulletins, Wiring Diagrams/Schematics, etc about your vehicle.

Hope this helps.

Sounds like a loose or burnt wire going from the transmission to the engine. Please try to remember who changed the oil last and ask them if they will look for a loose or burnt wire. The professional oil changers get in a hurry and might have hit an important wire to the transmission. How many miles would help answer the question more thoroughly.

i would check wiring at injector 6 for a bad contact if ok test injector

does your cruise control work? If not, check the wiring from the VSS to the speedo cluster. Check VSS connector closely for pin pudhout or corrosion

Sometimes, the VSS siganl is converted by the instrument cluster and sent to the PCM and speedo.

Check engine light on?


Speedometer
The electronic speedometer (17255) receives a speed signal from the vehicle speed sensor (VSS) (9E731). This sensor is also used to sense vehicle speed for the engine management system and to regulate the cruise control when equipped.
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Vehicle Speed Sensor The Vehicle Speed Sensor (VSS) (Figure 53) is a variable reluctance or Hall-effect type sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling.

plug ,plug wires, injectors. dose it do it when the weather is wet or cold or all the time

clocks are dead its a common fault they come on and off intermittently i had the same fault you need to replace your clocks

Have a mechanic take a look at your throttle position sensor and engine idle sensor. Make him manually adjust them as opposed to just putting in new ones. It may require that you have to have a higher idle than normal. Your underlying cause is going to be that I am sure you have a lot of miles on your engine.