MacBook Pro Trackpad – Fixing Crazy Trackpad on MacBook Pro 2011

Whenever I connect the AC power cord the trackpad behaves erratically. If I disconnect the computer sometimes returns to normal, sometimes not.

Some background:

• My computer is originally from the Americas.
• I'm currently using it in Europe with a European charger.
• It is running macOS Sierra.
• I modified some trackpad configuration on my other partition that I use for Ubuntu.
• I already tried resetting NPRAM and SMC and nothing changed.
• I repaired my disks using the Disk Utility, however I can't use the Recovery Partition. The loading bar appears but doesn't go away. (I have tried waiting over an hour.)
• The charger was given to me from my employer and it appears to be original and it also appears to be ok (in fact it was still wrapped in plastic as it appeared to be brand new).
• I don't have a way of testing it with other chargers and I don't exactly remember if it was happening before this charger. (It could have been).
  – Currently in my battery menu there is a legend saying "Condition: Replace Soon". I just replaced the battery for a new one and still is not working.
• Sometimes when this happens I run the following commands to recover my trackpad

sudo kextunload /System/Library/Extensions/AppleUSBMultitouch.kext to disable

sudo kextload /System/Library/Extensions/AppleUSBMultitouch.kext to enable

However sometimes a Kernel Panic error appears.
– The last thing I noticed is that somehow only when I use two finger gestures I "lose" the trackpad.
– A new discovery is that the keyboard also behaves erratically sometimes like ignoring key presses.

So that's basically my story. I don't really know what to do next, also I don't really have a way to replicate the problem. I just know that only happens when the charger is connected. Of course my MacBook is old but is really powerful.

To conclude, I ran Apple Hardware Test (extended) and everything appears to be fine!