Clicking noise

I have a 2002 type s 3.2 tl... i hear a clicking noise from my engine and i don't know what it is.. it speeds up when i go down the road but not so much when i rev the engine so its really not going by the rpms.. it sounds like somethings hitting... any ideas on what it could be?

did u change ur oil?? look for that, maybe u forgot to do it or ur engine is leaking

could be a injector...i'd say...

GOOD LUCK....