Go back to the dealer and get your money back. Seriously, that's BS. They didn't repair anything and if wiggling the wires makes it go away, all they did was repeat the symptom.
How did you check the integrity of the wires? Since 14 is ECT Low, make sure the grounds on the ECM are good and the ECT shares a ground with the MAP sensor. If you set your meter to DC Volts, the yellow wire should show close to 5VDC. J1-29 is the terminal at the ECM that provides the ground reference and J1-2 is the terminal sending voltage to the sensor. Make sure the terminal hasn't backed out of it's normal position. Make good notes and take lots of photos, in case you find what the dealer didn't bother to.
If your motor has had a bad overheat, inspect the wiring on top of the motor. I have seen the wire loom melt, which allowed the wires to contact the hot intake manifold, which melted the insulation and caused a DTC 15 code.