I have a 1986 Fiero GT and the idle has changed to 2500/2800.
I also have no idea why this would happen.

computer changed air/idle sensor changed.

Please help

Thank you in advance.

Rich

OK I got it the tube to the EGR had a major crack in it.

Massive vacuum leak.

You may try a new AIC (Automatic Idle Control) unit.
Bolts on to the side of carb.
Hope this helps...let me know. I have an 1988 4 cylinder.
My Fiero needs one right now. Will put it on this coming weekend.
GOOD LUCK!
JoeZamp

I was gonna say vacuum leak... LOL

Let me know how it goes RagTop.
Later
JoeZamp