What is causing my car to turn off?

Things I've replaced:
Fuel Filter, Throttle Position sensor, battery terminal, fuel vapor separator tube, Throttle Actuator control module, PCM, Crankshaft position sensor, fuses, spark plugs, ignition coils

Codes:
P2107- Throttle Actuator control modual processor
P0600- Serial communication link
P2105- Throttle Actuator Control system- Forced Engine Shutdown

I have a 2006 Ford Crown Victoria police interceptor with 110,000 miles. I have went to the Ford dealer to diagnose it and they told me that my PCM is bad so I bought one and it worked for a day until it turned off on me again and it still reads the same codes as the other one. It turns off on me about everyday and I have also replaced the Throttle Actuator module which I thought it worked for 2 days then it turned off again. The spark plugs were burnt out when I bought the car and they are hard to reach since the intake manifold is built weird. I do the oil changes when needed and I still not have seen any results.

Not sure but you seem to be interpreting the codes incorrectly. The code gives the location of the trouble or the sensor that is getting an unexpected (out of range reading). It does not mean that the particular part it points to is itself faulty. You have to look for what is causing that sensor or whatever to get the bad reading as it may well not be the sensor itself that is faulty. Could be for example the wiring to it.

The PCM shutting off likely due to a shorted sensor. You have to see a professional mechanic/specialist on engine diagnosis. Dealers do not spend too much time on diagnosis because there's not much money on it.

If you have changed the crank sensor, coils, plugs, wires, and PCM, how about the camshaft position sensor? They can give similar symptoms.

The codes are pointing to a possible wiring problem in the related PCM circuits or poor ground path connections… That's where I'd start looking since replacing items did not resolve the problem. Check for loose or corroded ground wire connections for the PCM and bad wiring /connections at the Throttle Actuator… TAC… Or ETB. Run continuity tests on the circuits or check for high resistance… CAN Bus connection points issues, check electrical connections for loose or frayed wiring, loose connector, corrosion, etc. You'll need a wiring diagram to trace wires between PCM and various items like the TAC or ETB… See link below… Listed under Engine Controls… Or Power /Ground Distribution.A factory repair manual would help too… Eautorepair.net or Alldata.com have factory repair info online… Small fee.

http://arrc.ebscohost.com/searches?car_uuid=1432106&filters%5Bservice_information_type_path_facet%5D=root%2Fmrt%2Fsit%2Fp5_diagrams&filters%5Bsystems_component_path_facet%5D=root%2Fmrt%2Fssc%2Fp5_engine_controls%2Fengine_controls_1_of_5
P2107…
"Possible causes
- Faulty Electronic Throttle Body (ETB)
- ETB harness is open or shorted
- ETB circuit poor electrical connection
- Faulty Powertrain Control Module (PCM)
http://www.autocodes.com/p2107_ford.html#ixzz44a8vWJet

P0600…
"Experience has proven that a poor connection or failed ECM driver is the root cause of this code. For the most part, the ECM acts as a ground to control these components and modules as opposed to supplying power to them. A loose or corroded connector is more likely than a frayed or broken wire between both devices. Poor grounds are another plausible cause. The ECM, as well as the activator module, need a good ground to operate. The wiring harness or Can Bus may be defective and have a short to ground or an open wire."
http://www.obd-codes.com/p0600
Copyright OBD-Codes.com

P2105…
"Possible causes
- Faulty Throttle Actuator Control (TAC)
- Throttle Actuator Control (TAC) harness is open or shorted
- Throttle Actuator Control (TAC) circuit poor electrical connection"

Read more: http://www.autocodes.com/p2105_ford.html#ixzz44aA2EJVS