Last night I co-piloted the 727-200 on a fairly uneventful flight. The only thing we did wrong was to select a RNav STAR which as it turned out wasn't too bad considering we were using steam gauges. I taxied the aircraft after landing & as the manual suggested cut the middle engine as it was going to be a long taxi & I wanted to be "thrifty" with gas (dunno why as it's free in FS anyway). So far so good.... when I stopped at the gate both remaining engines died! Although I would have killed them myself in a few seconds they should not have stopped by themselves. We had planty of fuel left so that's not an issue & the dump switches were not on. I don't think I had turned anything off at this point. Does anyone have any suggestions?