Nissan Repair: hesitating, mass airflow sensor, volt ohm meter

Question
i just put in a used motor with 65k in my 03 chilkoot, it runs and sounds perfect when idle, it picks up speed good but when i really step on the gas it hesitates so bad the vehicle jerks.  the mechanic who installed it cant figure it out and no test point towards the O2 sensor. the new motor we put in did come from an 03, but standard.

Answer
Geoff,

Check the mass airflow sensor with a volt ohm meter using the valuse given in a Haynes Manual and also check the throttle position switch.  Also, make sure all vacuum lines are connected at their correct location.  Hope you did not get rid of the old engine so you can compare sensors from the old to the new engine since the old one was from an automatic and the new one is from a manual.  It is important to transfer any sensors from the old engine to the new one to interface properly with computer.  Email me bakc with what you find and if there are any codes present.