I have a 2004 Kia Optima runs fine for a while.  It acts as if it is running
hot; however, the gauge temperature is reading normal. It does not indicate
that the engine is hot.   It will run fine on the highway, but as soon as I
am in the city it appears that it is losing pressure.  Therefore, I have to
pull over and wait for the car to cool off.

I have replaced the hoses and thermostat.  However, I am getting the same
results. The car will barely move and the rpm is off the chart.  Until I let
it cool, off.

I was told it might be a fuel filter. Does anyone have a suggestion what
could be wrong

Michael