1991 Honda Civic engine sputters after engine is warmed

12/6/07 After driving about 15-20 minutes the engine begins sputtering. I replaced the spark plugs and fuel filter a couple weeks ago. Yesturday I replaced the spark plug wires. The problem doesn't really occur if you give it a lot of gas. Usually I have to push in the clutch and rev it up a bit. Then it sounds like it has been cleaned out. After just a couple seconds though it starts sputtering again.