2000 Cadillac Deville I need help

Ok I have a 2000 deville with 150,000 thousand miles when I drive it down the road the check engine light will come on and flash when I scan it it throws up code p0300 wich is random misfire but it goes away and runs fine it doesnt do it all the time only every so offten I have replaced both coil packs wit oem parts from cadillac but now im at a stand still please help with any info thanks james