Why does my 2003 Lincoln Navigator keep stalling for no apparent reason. It doesitanytimeHighspeeddrivingandatidletoo

Unfortunately the only advice we can give is going to require *hands-on* testing using diagnostic equipment the DIYer isn’t going to have nor the experience to do so. There is no quick push button fix here. Suspect - vacuum leak - idle control - contaminated throttle body for just a few possibilities.