Which version of the VCMuzzler do you have? I would try two things.
1) To make sure the VCMuzzler is guilty, I would unplug it totally from the car and see if things go back to factory OEM. Sometimes we tend to blame other problems on the modification part. You might just have a bad thermostat, relay, fan or something else.
2) If the VCMuzzler is at fault, I would change the resistor in the VCMuzzler to a different one and see if that helps.
Hope this helps. At least that is what I would do if it were my car.
2015 Acura TLX w/ADV
ASE Master Tech
CSI Vehicle Forensics