Rough start and stalling after 2 days of rain

[DjCUF]

I just bought a 2000 XLT about a month ago and it's been running great with no issues. Last night it didn't want to start in the rain. It cranks strong but won't start. My first thought was wires or coil so I hit them with some WD40 but no help. This morning I got it to start by giving it some throttle but it dies as soon as I take my foot off the pedal. I tried keeping it running until it warmed up to see if that helped but after about 10 minutes at 1200 Rpms it still stalled instantly.
I cleaned the MAF when i bought the truck and put in a new battery. Did some normal minor maintenance like I always do when I buy a used car. What I really need to know is if giving it gas would cause it to start if it was a bad or wet coil or wires. I've dealt with misfires and stalling in the rain on other cars and ignition system is usually the problem but it's been years since I've had an issue like that on anything.
Is it just a coincidence that it happened in the rain? It's still raining today so I have no idea if it will run better when the weather clears up.

 

[Accarguy]

This is just a hunch but it sounds to me like it could be your Idle air control motor because of that fact that it will start and run with your foot on the gas. I could be wrong but this what it sounds like to me. I have never had any issues with mine.

 

[DjCUF]

After a little more research I think that's worth trying. I don't know if the rain would cause that or if it's just a coincidence but it's a cheap fix that can't hurt. I'm gonna check out the wires now that it's dark outside and see if there's any fireworks under the hood. I only paid $500 for the truck with 160k on the clock so even if I spend a few hundred replacing things that aren't the culprit I'm still making out ok for what I paid.

 

[DjCUF]

So just checked for arcs and there is no noticeable arcing anywhere along the wires or around the coil pack. Looks like I'll be removing the IAC to see what it looks like in there. Might just replace it and skip the cleaning just to save time and avoid any trial and error of wondering if I cleaned it well enough.
The more I read the more it seems the IAC is bad even if it's not the main issue causing the no start right now. When I first bought the truck I tried the AC just to see how it worked and noticed that the engine seemed to struggle when it was on. I've seen other people mention that could be a symptom of IAC problems too. I hadn't thought about it since it hasn't been AC weather in New England in November but that's another finger pointing towards the IAC.

 

[96eb96]

IAC may be the issue.
When were the plugs and wires changed last? The water/mist test isn't always accurate.

 

[DjCUF]

As far as I know the plugs were changed about 2 months ago. Not sure when the wires were changed. Once the weather cleared up I got it started after a few light taps on the IAC. Can't be sure if that was what solved the issue or if the coil and wires just dried out after a day of no rain. Either way it's back to running beautifully so I at least know that it isn't anything major. Gonna get a new coil, wires and IAC with the next couple of pay checks. Can never hurt to replace any of those after buying a car used.

 

[2000StreetRod]

which engine?

I don't know which engine you have but on my 2000 Sport with the SOHC V6 my engine will start fine with the IAC valve electrical connector disconnected. Of course it dies almost immediately because of no idle control.