Daltonk`

I have a 2002 blazer zr2 I am having a problem with a random cylinder miss it does not set a fault code. It will just flash the check engine light under a heavy load or hard acceleration and set a pending P0300 fault code. I have a higher end scanner that allows me to watch and record all the sensors and nothing looks out of the ordinary besides the 3,000 miss fires on cylinder 4 and the 2800 on cylinder 3 in one hard 0 to 85 pull check engine light starts flashing in 3rd gear around 3,000 rpms and keeps flashing until you let off the throttle. The plugs and wires and the cap and rotor are about a year old the spider injector assembly is about a year old. Any ideas on what could be the problem and help would be greatly appreciated.