Transmission no overdrive

Hi guys,
2002 Focus LX, automatic w/99k miles w/air. loses gears when going from 3 to 4 sometimes from 2-3. So I can't get it over 40mpg. Disengage overdrive and seems to run okay to get higher speed. But engage O/D and gears are lost.
Fluid seems okay. Any ideas or is it shop time to be sure?

i wasnt aware that any focus could get 40mpg. maybe its just me but mine seems to get pretty poor gas mileage

I think He meant 40 mph

you know that would make a bit more sense

When I drove to NC from CT a couple of weeks... I got 37mpg at 55mph~60mph. Mine is 2002 zx3.

okay 40 mph... I'll get 35-36 mpg consistently... 40-50 mph coasting downhill

hakebros,
I am having exact same problem with mine. Any feedback would be appreciated.

Thanks...