Can a fuel filter cause bad emissions????????

A partially clogged fuel filter will only be evident under high fuel demand situations, i.e., accelerating. The emissions checks do not put the engine in a high fuel demand situation. When you say that the car is running OK, I assume that means also when accelerating in normal driving, therefore it is doubtful that the fuel filter is restricting fuel in a way that would affect the smog check results.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

No, the fuel filter isn't causing your emission failure. It's some other example of your gross neglect that's doing it.

Have the spark plugs ever been replaced on the car?

How about checking junkyards for converters.

In the U.S., it is a violation of federal law to sell (or buy?) a used catalytic converter. Many (most) junk yards have some government sign (or commercial sign quoting from the regulation) hanging on the wall of their counter area explaining, so that when some customer gets irrate that the yard refuses to sell them a cat, all the counter guy has to do is point at the sign.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Has your muffler been replaced lately? A new muffler can sometimes cause problems in the test.

Check for fault codes in you engine controller. Probally, your oxygen sensor is bad.