If the shock sensor harness has it's own little plug (4pin usually) you can just unplug it versus clipping the blue/green wires. Judging from the online install guide, yours does, so you can just unplug the 4pin connector from the side.

If the sensor's blue/green wires connect to a larger connector, one that also has wires like Ground (black), +12V battery (red), purple (ford+ doorpins), etc. etc then I would just cut the blue/green wires near the sensor.

The sensor will still have power, but it's a minor amount of current draw. Be sure to leave yourself room to reconnect it later (leave a couple inches of wire on either side), and make sure the cut wires cannot short to ground, which would trigger the alarm.

There is another option... move the sensor to a more solid place in the truck. Something attached directly to the frame is often less sensitive than when it's attached to a plastic bracket. You could also be detecting the shifter vibrating, or something around the sensor. One of the more popular places to mount a shock sensor is zip-tied to the steering column (on a shaft cover around the column that DOES NOT move, of course. ). Last, but not least, sometimes the sensors are directional.. turning them 90 degrees may help improve their performance.

Personally, I like the high dollar ones, like a clifford Intellisensor (uses DSP to analyse detected vibration, triggering on an impact only, not vibration). They were expensive ($100!) but you could park next to a diesel train engine and not false, yet hitting the door with your fist would trigger the alarm. Plus you can change their sensitivity in 30 seconds by doing little more than pushing a button and hitting the car at the level you want it to trigger on...

But, if you monkey with them enough, the cheaper sensors will work just fine.

Good luck..
-=RB