'91 nissan maxima problems

Hi everyone, I have just purchased a '91 nissan maxima, and we were told it had problems with driving, we changed a whole bunch of vacuum lines that were damaged under the hood, the problem with the car is that when u put it in gear it surges then stops surges then stops, sometimes it runs GREAT when u can get it goin, also sometimes it doesnt go into a gear mainly Drive...the guy said he rebuilt the transmission,added new fuel pumps, alternator... if anyone has had prior problems like this or know whats wrong please feel free to help me out, thanks P.S. I've been told that it could be sensors or a vacuum hose to the trans or even a short in the car