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