Missing At 80 mph

[jbb421]

So my 2004 6.0 is missing at 80 mph if i hold it there with my foot it isn't as noticeable as when im using cruse, but its still there. it has a miss when its cold only when its colder than 40 degrees outside but when it warms up its perfectly fine, and also if i run cetane boost the miss goes away ive tried getting fuel at other places but it does the same thing usually or worse. The Ficm is reading 48.6 volts, ive also deleted the egr, new head gaskets, head studs, oilcooler etc.. about 20k ago. It doesn't smoke on start up nor give any troubles. Also has plenty of power and only misses at 80 if you stomp it from 80 the miss clears up and takes it off, or if you let out of it its fine also. No trouble codes either.


Thanks jbb