2000 es300 no start

hi guys looking for help here...i just installed a used engine into this vehicle which is the 3.0 6 cyl. theold one ran fine and started right up except for knockin. i went back and double checked that i have all sensors connected andstill wont start. i tried starting fluid...the one lug i checked had spark and all the front plugs were wet with gas when i pulled them also. i dont undersatnd the problem and need someones assistance