Make: Nissan Maxima, Model : A32, Year :1995, Mileage:142000

In the last three months I noticed that the car will go off in motion and sometimes it will jerk. This problem subsides but is not eliminated when the air conditioner is off. Also noticeable is an accasional fluctuation of the tachometer reading.

In trying to get it fixed the following parts have been changed: air flow meter, fuel pump and air filter . The plugs and fuel filter have been confirmed to be okay. Now I'm being asked to change the brain box.

Before I do any other thing, please advise me.