Problem with idle on startup

[JakeVII]

A few days ago my 1991 3FE FJ80 was struggling to start. It would fire, climb to 500 RPM, then die. When I started it and hit the gas pedal, it started fine and runs well on the road.
I did the valve timing, replaced the PCV valve and grommet, replaced the EGR valve and replaced the EGR modulator.
After this work, it started but it kind of hanged on 500 RPM, then it fires up the rest of the way. I don't like how it lingered for a second and a bit at 500 RPM...
Why might this have happened?

 

[SUMMIT CRUISERS]

Two things come to mind: if it only acts this way on a cold start, then your cold start injector might not be working properly. Also a small crack in an intake hose (or related hose) might also do this as well.

 

[JakeVII]

Two things come to mind: if it only acts this way on a cold start, then your cold start injector might not be working properly. Also a small crack in an intake hose (or related hose) might also do this as well.

Nice. I'll check whether it happens on starts when the engine is warm.

 

[JakeVII]

Yep, no problem on warm start. I cleaned the cold start injector about a month ago and pulled a lot of gunk out of there. I'm going to clean it out again and see what's going on in there.