ECU INSTALL/ MISFIRE

[infinitioverload]

Hello everyone I really need some help here. I have a 1998 Infiniti Q45 it runs good and everything but i noticed that it was misfiring a few weeks after I bought it. However it was only when it came to a complete stop. I brought it to a mechanic shop and the spark coils were brand new, the fuel filter was brand new, the Maf was fine, the idle control valve was clean and working and the EGR Valve was also clean. Anyways the mechanic Diagnosed the car and realized that it was the ECU and that the car was running in limp mode. So i decided that ill just buy a ECU and set it up myself instead of paying nearly $700.00 for the part and the install. My question is if I by the computer that matched the manufacture number on the old computer is it plug and play? or do i have to bring it to the dealer to get programmed to the car itself along with the key? Cant i just unplug the old computer and install the new?

Any information that can be provided will be greatly appreciated. Thank You so much!