1999 Ford Ranger idle and acceleration

Engine Performance problem
1999 Ford Ranger 4 cyl Two Wheel Drive Manual 153.00 miles

I have changed what the computer codes have said.
2 Oxygen sensors EGR pressure switch, EGR vacuum switch, checked for vacuum hose leaks, replaced 2 year old spark plug wires with new ones,
Mass air flow sensor, was not on code but I changed it any way. My spark plugs are only 1 yr old and they are top of the line Bosch.
Last Saturday I replaced the valve cover gasket and I was extremely careful not to get any thing in the motor and this fixed my oil leaks.
acceleration is sputtering and idling is rough power is not their.
I take very good care of my truck so I am at a loss for what it could be