1988 305 TPI, so sometimes it will start up flawlessly, but other times it'll die if I don't sit there and give it gas for 2-3 minutes, and even after waiting I'll be idling at 500 rpm. My idle ranges from that 500 to 1300ish, solely depending on startup. This is when it is both warm and cold out.

 

Do a search on here for "TPS and IAC Setting procedures. Sounds like it could use it.
Also check for codes.

Here.......It's your luck day. I done it FOR you. Open the link up and follow it to a "T"
https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

It should help.