99 5.7 Hard miss

I've got a weird hard miss that occures in overdrive or in 3rd in my 350 auto matic . The truck runs exellent,always.. but periodicly as the trans shifts, in o/d, and it gets thru to cruzing gear, it misses or (hickups) untill I give it more gas,then it shifts down and goes away.I figured I had a o/d gear problem , but it seems to creep up in 3rd from time to time as well ? Background...new cap,wires,fuel filter,plugs ect TNX B