Battery new, alternator tested loses power dies at stoplight on 2000 Mitsubishi Montero

After new battery installation, 2 days go by and the suv lost power, returned to repair shop and problem was diagnosed as "electrical" problem. No one will service

Asked by for the 2000 Mitsubishi Montero
Joe'. I know this doesn't help U today, but for others: This is common on these (mine is a '99 / 3.0). The reason is that as the Crankshaft Seal weeps oil, it sprays lightly enough over time, where it coats the Alternator (and eventually the Starter) and it / they eventually get compromised & then eventually fail.
Our Alt. lasted about 3 yrs / 25/30K mi. before it failed again for the same reason. Anyway, when the battery fails, the 'memory' in the computer which contains all of the 'Starting / Warm-up' curves in order to set the correct idle fuel mixture, etc. , has to re-learn things. So after about 5 --> 10 starts / warm-ups, your idle ought to be fine. But make sure that: your Battery Terminal Connections are tight, and that your Alt. is actually *good*! Then U ought to be all set. Probably the simplest "Electrical Problem" you'll ever have!! - M.H. / Rochester, NY