1997 Ford F-100 misfire PO301 PO304, PO306.O2 senor to lean

Hi guys I got a head ace again!Truck came in with light on hook up to sacnner codes where.
po301, po304, po306, o2 sensor to lean!Things I did.
1-check o2s had 1 that was not responding read -3.0? Unplug it did not change. Replace it (good).
replace spark plugs they were foul bad replace coil pack and wires, fuel filter was never changed replace. Claer codes run good!Then light back on cly.4, cly 6 and down stearm o2 sensor change o2 clear codes light comes back on.I check for vacuam leaks fuel presure 30 lbs. Any help you can give?I have 3 days in this one and even check for bad grounds!