91 f150 w/5.8 eng efi, AT 4x4. Truck starts real easy and the idle is smooth when warming up but once it gets to operationing temperature it will cut out. It appears to be a fuel caused problem to me but maybe not. Whatever the cause the vehicle rpm drops 200 - 300 intermittently but never dies. When I raise the rpm to 1200-1500 I do not detect any missing. Any ideas out there?