1997 Geo Prizm

I bought this car used - slightly over 100K miles, no problem 4 years except fuel filter needs replacing twice already. Is this normal

Twice in four years? Dirt in fuel tank? (Plastic tank right? no rust)
I’ve let my van and suv go to the 3 year mark a few times with no performance problems.

On the other hand if you load up with bad fuel along the way (unknowingly), it may be wise to change more often than not.

Letting a fuel filter change go too long CAN cause premature wear in the fuel pump.

Did you look at the filters after they were removed?

I’m also wondering of the fuel pressure is low due to a worn pump or regulator. It might not have the pressure to supply the system if the filter becomes even a little bit restricted.

As shown at the Gates belts (etc.) site: http://www.gates.com/part_locator/index.cfm?location_id=3598, you’ve lucked out. Neither the 1.6L, nor, the 1.8L engine is listed as having an “interference application use” timing belt. You got the car at a mileage (100,000) that’s usually the maximum mileage to change the timing belt. ----- I’m betting it wasn’t changed. Do you have repair records showing that it was?