Ford Repair: 2000 ford mustang gt, jumper cables, altenator

Question
The car decided not to start, so I did the usual and got out the jumper cables.  Let it charge for a min got it started and as soon as the cables were off it quits.  I got it going again and al long as it is not idling/below 2000rpms it will run, not as good as normal, and then stall out again.  The battery tact shows that it is getting a charge, but when you first start out to meters all jump high then fall back then high then back to normal.  Any suggestions as how to figure out where to look.  I just got it back a little over two weeks ago from getting a new motor

Answer
hey there, sorry to hear about these troubles. I would tow it back to the people who did the motor to begin with, someone may have forgoten a connector, are a ground strap, or something along those lines, and it may be a good idea to have the altenator tested. it it does start and run with the cables on it the dash will be showing the charge of the vehcile that is boosting that batter. if it dies as soon as you pull the cable off that is a very good sign of an altenator not charging, good luck
Chris P