Sluggish at low rpms
 

I have a 2004 mazda 6, 2.3l just got done replacing the engine old one went bad due to bad habbits in changing oil got a new one from the junk yard had it installed by a mechanic friend. The car starts fine and is as quite as when I first got it. Problem is when I accelerate it is very sluggish at lower rpms I replaced the plugs and wires I am thinking it might be a vacuum leak or the timing any thoughts or suggestions? There is no Check engine light on either.

I have found this is a timing issue now I am faced with messing with the timing I have a old engine I am looking at and I am not seeing any timing marks any help would be great if you know anything about this. Is there a special tool needed for this?