Intermittent low idle in drive+dies on initial acceleration

[hgeranium]

I have yet another idle issue, maybe the same cause as my other idle problems, but with new symptoms. I’ll try to keep it concise

 

So, this has happened three times in the last week. It starts off that the trucks idle sound changes as I slow down at a light, the idle is pretty rough and much lower than it should be (between 500-600, while park/neutral idle is ~750). The first time the idle crept so low it just died. Turned the truck on and it drove fine on the way home. The 2nd and 3rd time, I noticed the idle was off while at a light, and as soon as I took my foot off the brake, it died. Started right back up both times, idle fixed.
 

After the 2nd time I switched back to my old IACV yesterday since I replaced it a few weeks ago, but the 3rd occurrence just happened 10 minutes ago, so that didn’t fix it. 
 

I have an inkling that it’s an IACV and my old one+new one are both bad, because my idle in park and neutral are fine. When I knew the truck was going to die, I could put it in neutral and the idle returned to normal, then back to drive and it went back down. Am I missing something else or should I get another IACV?

 

All vacuum lines are good, cleaned TB and new TB gasket, manifold bolts tightened (still need to replace gasket), TPS set correctly. I feel like it has to be the IACV since it’s an idle issue only seen in a driving gear that fixes upon startup, so it may be sticking?

[89 MJ]

I’d try cleaning the old IAC first. And definitely swap that gasket. That might be causing weird stuff too. 

[hgeranium]

11 hours ago, 89 MJ said:

I’d try cleaning the old IAC first. And definitely swap that gasket. That might be causing weird stuff too. 

I’ve cleaned the old IAC to no avail a few times in the past. I was using berrymans. I know not to mess with the pintle but it’s OK to pull that sleeve down and spray in there, correct? More so asking for forgiveness rather than permission because that’s what I did lol

[pizzaman09]

I'd check to see if your manifold bolts are tight, you might have a big vacuum leak.  My truck did that when I purchased it and it turned out the manifold bolts were the culprit.