I have a 2002 Sport Trac 4 wheel drive since practically new I have had a prob with a loss of power after the truck sits for while. when I restart say after being in a store or something the truck has very little power and stalls I have taken it to my mech several times he can't find anything wrong. After I turn of ignition power for about 10 minutes the engine then runs well for another period of time sometimes months without trouble. I get no error code or Check engine light, doesn't seem to be any rime or reason to this. Have checked the cat and the mass air flow sensor and several other components. HELP