My step daughter was out of gas so she rode the bus to school today. I needed to make a trip to the auto parts store so I figured what the heck, I'll take her car and put some gas in it for her. The idle has been high since we got it but seems to have gotten higher. When the car is not in gear it will idle near 2,000 RPM even when it's been driven and warmed up. Idle in gear isn't bad (1,000 RPM).

But the more concerning problem, and perhaps it is related. The car sputters if you push the gas pedal hard. I usually always accelerate very gradually and had never noticed the sputter before. But today I had to goose it a little as I was pulling out and when I did it sputtered as if it wanted to stall. I immediately pulled my foot back a bit and it accelerated fine. I finished my trip to the auto parts store and when I got it home I tested this some more. It seems that you can push the pedal all the way down without sputtering as long as you do it gradually. But if you go from no gas to a quick hit of the pedal more than half way it sputters.

The car is an 84 with an automatic.

Pull your codes, find out what it is telling you here:
https://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

Buddy Craig can show you how to pull said codes here, using only a paperclip and a t15 torx driver:
http://www.youtube.com/user...g#p/u/67/sRoSMhEL3Ms

lol- I just typed this same message for someone else. Anyhow, once you let the car talk to you a little, cross reference the codes with my first link, and come back here and tell us what it said. My car idles fast, but comes back down to 800-1000 rpm after a while.. that may not be an issue. You might have a fuel/air mix problem that is causing your sputter, but I also am wondering if its not ignition/timing related.. I could be completely wrong though.