Loss of Power in hot weather/timing retarded

[rkerby]

My 02 Expedition losses a tremendous amount of power at operating temp. The power loss acts like the timing is retarded. It seems to have something to do with the air temp outside as much or more than the temp of the engine. Local Ford dealership said that in this vehicle when the outside air temp reached 100+ degrees the timing would be retarded to prevent pre-ignition knocking. But this service manager also said that there was a software update to widen that temperature range and keep the timing from being retarded until much higher air temps. He supposedly updated the computer but it has not fixed the problem. The fuel filter has been changed and the plugs were supposedly changed by the dealer prior to us purchasing it used about 6 months ago. It currently has about 75000 miles.

What sensor detects the outside air temp? I thought it might be bad. Or could a bad coil create this problem?

Any help is appreciated.