Cold start up issues

[Nez'sRanger]

Well, it's getting colder here in PA, which has apparently revived an old issue I had forgotten about. It will start up instantaneously, and really strong, but then die when the idle tries to lower (within seconds). I'll restart it, fires right up, never gives issue again till the next morning.
Any ideas? It's not end of world stuff, but it's certainly annoying.

 

[Dirtman]

ECT sensor can cause cold start issues. It is the EFI equivalent of a choke so if it fails it doesn't richen the fuel/air mix when cold.

That and when's the last time you did the basics? Clean the IAC and throttle body, clean the maf, replace the fuel filter etc...

 

[gaz]

Clean battery terminals, possibly replace battery wires.

 

[Nez'sRanger]

All of those have been replaced within the last year, which is why I'm a bit baffled at it.

 

[RonD]

+1 on the ECT sensor

If you have replaced it, the sensor not the sender, then check its connector, make sure the contacts are clean and the wires are not frayed
As said the computer uses this one sensor to set higher idle and CHOKE for a cold engine
Its a tight 5volt range, so .3volts means alot

Chart here: https://www.explorerforum.com/forums/data/xfmg/thumbnail/24/24365-f43791dd2506145a330fe2baceeba107.jpg?1583516355

difference between 68deg and 86deg is .4volt

32deg(freezing) is 4.14volts, just FYI, but 4volts or higher is FULL CHOKE

On start up engine should REV to 1,500+ RPMs, thats the IAC Valve being wide open for start up, that should happen warm or cold
Then if cold, RPMs should drop to 1,100-1,200, and stay there for a minute or two
Then as coolant warms up a slow drop to 650(manual trans), or 750(automatic)

 

[Nez'sRanger]

I'll double-check when I have some free time for sure! Thanks for the help!