replacing pipes under driver's side door

what is the pipe called that runs under the driver's side door and i'd like to know how i replace it if anyone knows

It's the driver side coolant pipe. I think that's the one you are refering to. I haven't had to replace one yet, so I can't be any more help than that.

The coolent pipes are held in place by a couple of metal brackets (probably now corroded into oblivion). You may be able to find replacements from Fiero used parts places www.thefierofactory.com www.kickhill.com www.twinlakesfiero.com . Each coolent pipe right vs left are different as are the years and engine coolent pipes. If you call, state the year Fiero and engine, then hope they have them.