I found this thread from several years ago but like a lot of threads it was never resolved. I have a screen shot and a link to the thread, just want to get some info from anyone who can help as I very occasionally get this same issue where it starts strong at 1000rpms but will momentarily drop a few hundred rpms then rise back up and all is normal after that. Not a big deal just a little annoying and I'd like to try remedy it.
Mine is an 88 T/A 305tpi.
https://www.thirdgen.org/forums/tpi/628669-rough-cold-start-up.html

 

Iac is new and clean, tps is new and set to
.54, fuel pump and filter new, new fp regulator diaphragm, cold start injector seems to function fine, injectors were serviced and cleaned 6 months ago, if that all helps.

 

If you have the equipment to log data, it would be helpful. There are several routines which affect target idle RPM, and some which add IAC counts based upon time since start, and CTS and IAT inputs affecting the target RPM before the start timer has elapsed, Then there are adders which are consatantly active. Determining whether the IAC is tracking the target RPM or is being affected by adders could be a critical step in determining the reaon(s) for the phenomenon.

 

Thanks Vader. It is quite the phenomenon given its inconsistency and that it happened before I did a ton of work on the car late last year with the old parts and still does it with all the new parts.

I figured data logging would be my only real option, it's hard over here in Australia to get that done even at workshops that specialize in American cars. I'm hoping to pick up one of the old snap on scan tools on ebay from the us but I'm a bit hesitant cause they're still quite pricey and if it arrives over here and it's crap I'm out several hundred $$.

I have heard people mention an android based scan tool, do you know anything about them?

 

It is also possible to use TunerPro V5, Moates, EFI Live, or other applicatons to read ALDL date directly. I can understand that a used Modis (MT-2500) can be a risk, and may not reveal all the data you would like.

 

Mine did this intermittently, was the computer temp sensor having issues (CTS). Swapped that, it's been fine so far.

 

I use this scan tool, can be found on ebay, and matched with aldldroid

Works pretty well!

Here's a screenshot of the data provided.

It can also be hooked up to tuner pro if you get the compatible model.
http://www.1320electronics.com/products.html



*Do disregard the data shown. This was from when I was ironing out some issues.