If the cold start injector has not been working for some time (whatever the cause), then it is possible for it to get clogged up from non-usage. It might be worth taking a look at, since even if you solve your problem somewhere else, the injector may still not work.

Just my experience, but a clogged fuel filter usually causes your engine to sputter when it's under a load. Although I wouldn't limit it to just that, that is usually where the problem first occurs.

To the original poster, I would change the distributor cap and rotor, and maybe even the spark plug wires, especially if you don't know how long they have been on there. It doesn't cost much, and I like to know how long they've been there. It may not make much difference, but it makes me feel better. Of course, that's just me. As for the rotor, it should pull straight off (grasp and pull upwards).