Hi, I am having an issue with my fiero that I need help with. Its' an 86 SE, 6cylinder, 4 speed. The problem; the car will randomly 'stick' while I am shifting, so that I have to force it into 1,2,3 or 4th. The next time I use reverse, it grinds. Other times the shifting is fine, hot or cold don't seem to affect it.The grinding just started this year. But here is the cars' history regarding repairs that might be applicable.
2010 - New clutch, fly wheel turned [done by mechanic that charged me for changing 6 spark plugs but only did two]
2010 - Next went to a transmission guy who fixed the linkage arm and replaced plastic bushings with new brass ones. At the same time he lengthened the shaft on my slave to put extra play in the pedal. He was a short guy so he had trouble getting the pedal to the floor. I have long legs, not really an issue for me.
2014 - grinding problems with all gears.
2014 - New reputable mechanic has so far replaced master clutch cylinder, slave cylinder [put in normal length rod, to remove play.] checked/adjusted the shift cables and mounts, all seem to be ok. He also straightened the clutch pedal.
Any ideas on what might be causing the stick and grind and how to fix it would be greatly appreciated. Thanks.

First thing is lengthening the slave rod is really not the answer.
It will only move so far and the rod length over stock may place the slave seal in a more interior location but it will still only move the 3/4" or so required to disengage the clutch. check that measurement. It could be a bad master or slave cylinder.
have you replaced the fluid in the line and bled it properly?
As long as the cables are good (have you disconnected them to see if they are binding?)
What fluid is in the tranny? how old is it?
is it the correct clutch installed?
There is a problem with the clutch peddle bending over time, check that. (many posts here about it)
Rodney has a replacement for the peddle I believe.
Just a few more things to check.
Let us know how you make out.

Maybe it's the clutch pedal assembly.
Over time, that pedal will flex or bend, preventing full clutch disengagement. (As quoted from the Fiero store.) I have an 88 and will have to change mine.

Rapidly pump the pedal to see if the grinding goes away. If it does, you have air in the hydraulics.

A bigger worry would be that Mechanic who installed your clutch. One indicator of a worn out clutch is getting grinding into reverse, although that is not conclusive.

Definitely get the new pedal. It's worth it and once the pedal has been bent, the re-bend even easier because the metal is fatigued.
Check to make sure your clutch pedal pad is above the brake by almost 1.5". This will cause you grief if it isn't. (This one bit me).
Gravity feed/bleed your clutch line and finish up with bleeding slave. Pulling bleeder is much easier but will cover you in fluid if you're not careful.
It's frustrating. But hang in there!