no egr valve so what does it use

What is your question?

been chasing a problem on my truck, p0300 code and i have changed plugs, wires, intake gasket and some off the coils. But 5 and 8 still are mis-firing at highway speed but not enough to feel, the engine rpms go up about 500 and the ses light flashes. Somtimes i go for a day or two with no code . checked the wires on the injectors and ran alot of different injector cleaners through the tank Still have problem. If it had a EGR valve i would think it was the problem so i thought maybe it was whatever they are using as a egr system Help Me please