140K miles and first sign of trouble is smokin to beat hell and running rough at idle. no oil in the coolat, no coolant in the oil< check engine on and holding codes that are for misfire on cylendar 8 and an unbalance code. runs great when warm. we put the truck through the diagnostic on the code reader and the fuel inectors show good and the glow plugs show good. i think inector is goig bad but not sure what to check before i take it to ford house i thought i would ask here, any ideas what to look at?