2003 Cavalier

 Does anyone know what would cause my car to loose power while in commute then immediately pick back up again.  This has happened to me several times in the last 4 days.  I have my foot on the pedal and it boggs down.  I did not notice any jerking, or noise.  I was thinking it might be a fuel filter. 

do you have high mileage? when was the last time that it was tuned up? have you followed your maint. schedule?

The car has 50 k miles on it.  Yes I have followed the regular maintenace schedule.  I had the fuel filter chaged at the recommended mileage.  I thought I might have somehow got some stuff in my tank that is clogging the filter.  I am not sure.  I do know that when my car reaches the 1/4 tank mark is when I have the problems.  I fill the tank and the problem goes away.  I paid attention when I filled the tank the last couple of times and it took 10 to 11 gallons to fill it up, so I know the gauge is not off.  I have a 15 gallon tank.