1988 Pontiac Fiero...

[Dee-Dee]

...Fast Idle.? I've got major issues with this, because not only does it consume way more fuel when doing this, it also gets dangerous when trying to stop on a wet road. I've replaced the IAC sensor, TPS, checked all vacume lines, checked fuel lines for leaks, replaced air filter, checked; PCV, hose, and filter, replaced Fuel Injector, and replaced MAP Sensor. All that's left are the ECM and EGR valve...
I checked the EGR though and it sputters and dies when you fully open it by hand, and by diagnostic logic, that means it works. The only other problem as far as engine performance goes is when it isn't idling at 6k rpm it either idles right, or doesn't idle period. There's supposedly a sensor on the engine that tells the transmission when to mechanically "lock-up" but as far as I can tell it doesn't lock-up ever...
Already checked hose from PVC to Intake, and used a tube and cigarette to check for leaking lines as well as poking and listening with a piece of hose.
Also checked throttle cable that was my first thought, everything works smoothly. there's no buildup in the throttlebody it's shiny and new looking. Keep trying.
Haven't checked the brake booster line, but I know it's working, I got good brakes. And the injector is spraying conical-like cone...

 

[lexusry]

make sure throttle cable is not binding.next, remove throttle cable from throttle body,make sure the throttle valve open and close easily.make sure throttle plate is clean from carbon deposit. use a smoke machine to look for vacuum leak. visual inspection is not accurate.

 

[Changed]

Seems like you checked most everything.
One thing that I would check is the the tube connecting the air filter to the intake. If there is something lodged in there. you will get high idle conditions. I know this from experience. this causes the throttle plate to stay stuck open. also, make sure that the throttle is not sticking, (also causing the throttle plate to stay stuck open. mabe the throttle cable is binding and sticking.

 

[Red]

Check the spray pattern on the injector. Could be dribbling and squirting instead of spraying.

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[homeless in hell]

try checking for vacume leaks behind the engine. there is a vac line going back into the firewall that goes to the brake booster up front. Check that as well as the connection up front too.
Otherwise check for intake manifold and throttle body leaks. Disconnect your iav and see if it dies.