Idle too high, dont know why

I own a 87 lxi fuel injected, i seem to have problems with it starting sometimes. Sometimes it will start good and right away without the PGM-FI light going on with my idle being at about 1200 but when my PGM-FI light goes on my idle goes up slowly to about 2000. I would be pleased if someone could help me or give me some advice I dont want to take it to a mechanich because I want to do it myself.

you need to check the ECU for codes. https://www.3geez.com/showthread.php?t=26342
what ever it is, it is causing to idle high.
even 1200 RPM is way too high.
your idle should be around 700-800 rpm.

definately check the codes, when that light comes on, your car goes into a "failsafe" mode. It increases fuel consumption drastically and you won't pass emissions most likely.