Replaced IAC just over a year ago, and same problem of not holding idle, fluctuating RPM and stalling.
OBD code said it was the same problem last week, so I replaced it.
Will not reset after driving over 40 mph per the instructions, idling at around 1500 rpm.
Checked connections, can't find a vacuum leak. When I replaced last year, I pulled the intake manifold ( carboned-up nightmare) and cleaned it thoroughly- so I know it's not a dirty manifold.
Computer was also replaced last year.

Is there a different trick to get the computer to correctly "clock" the IAC at idle?

 

You can try resetting the computer by removing the battery connections, wait for a couple of minutes, then re-connect them. You might also want to double-check the rear of the throttle body to ensure that there isn't any carbon back there in the well where the IAC bolts on.

 

This.

Make sure the throttle body is squeaky clean. (remove it from the intake, and clean it out, leave the battery disconnected while you are doing the cleaning. If it doesn't really need cleaned, disconnect the battery, turn on the headlights, count to 10, turn off headlights, reconnect battery) Once everything is hooked back up, turn the ignition to On, (not start) count to ten, (don't touch ANYTHING while you count) THEN start the truck. PCM should figure out idle fairly quickly.

If you have an aftermarket IAC in there, I have found that they basically suck. They simply don't react fast enough, and unstable idle, and stalling are the result.

 

Kinda what I was thinking... just went through this. $40 seems just too "cheap" to be reliable for this component.
I'll do as you suggested- if it doesn't work I'll call the local dealer for OEM.

Thanks!

 

If you can get the OEM part number, you can search (with google) on the part number, and likely find the genuine OEM part for less than the fortune the dealer is gonna want.

 

I discovered many thing on this site thru the gurus, high priests and disciples of their mastery of the mopar mystery. I hope my list will help you in your endeavor.
I have owned a '96 Ram 1500/5.2 since new, low miles driven these days (daily driver/utility vehicle) due to gas prices...still around 250K miles.
But I digress, three things I discovered to be of uber importance to engine drivability issues on my beast...
1) do the keggar (intake) reseal, even hughes mod (my intake air temp even seems to be a little cooler on average, prolly due to plenum base thickness) and oil resistant sealer along that damn leaky gasket,
2) install even a simple oil catch can for the PCV (mopar only) system, and,
3) replace those stinkin' cheap *** factory valve stem oil seals with some fel pro ones. With those 3 little things, I think I cured almost 99% of my usual Ram 1500 5.2 issues. Idle problems, none in over 5 years, and throttle body or IAC never needs cleaning anymore. Oil consumption down to around 1/2 qt per oil change (3K/lotsa city driving). AND last but certainly not least, my spark plugs don't get carboned up anymore and last a very long time now.
I just wish the distributor cap n rotor were as easier to get to, mine are almost 10 years old now...grrrrr! Time to yank her out again, I guess.

 

Soooo....
After weeks of driving with high idle, reaching out here one last time...
Replaced the IAC with OEM one- found one on Fleabay, sealed Mopar pack (10 year old date code, but correct part #).
Same problem as with the aftermarket, so I'm thinking it's not the IAC after all. Still throwing the IAC code, no code for the TPS, my local parts guy thinks it's a vacuum leak.
Symptoms:
At cold start, idle isn't all that high- about 1000 rpms, but fluctuates a bit.
Once warm, idle at about 1,400.
One oddball symptom might help diagnose: At speeds above 50 mph, if I just take my foot off the accelerator and allow the truck to coast, the engine will slow the truck to about 40 mph and 1,000 rpms.
I've noticed that as soon as it hits 1,000 the rpms will rapidly "bounce" between 1000 and 1,400 three or four times- then remain at 1,400. RPMs remain at 1,400 in neutral, just over 1,000 in gear with foot on the brake. Probably not doing my tranny any favors.

I had a problem previously with the maze of skinny vaccum lines in the area of the AC accumulator that was causing the climate control blend door to bounce around every time I accelerated (found a cracked line and fixed it), that's not happening and I can't find any obvious breaks.

Parts guy suggested I take it to the mechanic to do a smoke test to see if it's a vaccum leak, even though I'm not getting any codes for that.
Sound advice? Anything jump out with the symptom above as to where else I might look for a vac leak?

 

What temp is it out when you cold start it?

 

Is that a P0505 code??

Unplug the IAC, turn the ignition to run. Don't need to start the motor. Use your volt meter, or even a test light, and check all four pins for voltage. Should see 12 volts on two of the pins. Do you?

 

what does the outside air temp and intake air temp read?