Fuel injector?

i have a 91 s10 blazer, when i started it this morning it was running really rough, so i opened the hood and heard some sort of clicking noise, i took off the cover for the air filter and noticed that, that noise had gotten much louder, after it warms up to about 150 degrees, then it seems quite a bit better, but still noticeable, has my fuel injector gone bad?

I would suspect that a failing lifter is more likely.