Could this be the culprit?

[91stranger]

So upon searching google for what all can cause a P0455 code on my ranger I found the filler neck could be at fault. I knew it was rusty and getting bad but I just took a picture of it and I think I found my evap leak. Now could this be causing my truck to stall at idle while driving like when I let off the gas to come to a stop? I'm tired of stalling while driving. Especially when I have the kids and baby with me.

 

[RonD]

EVAP issue would be unlikely to cause a stall, might but not likely.

Computer uses IAC Valve to control idle RPMs and it is very responsive

When you take your foot off the gas pedal the computer should see under 1 volt from TPS(throttle position sensor), .69-.99volt is spec
If your RPMs are above 1,500 at that time, i.e. coasting downhill, computer will shut off fuel injectors to save fuel, under 1,500 it will set them at idle fuel levels and use the IAC Valve to set 625-750 rpm idle(manual-auto trans)

Speed sensor also plays a small part in the above

After engine is warmed up fully
Let it idle and unplug the 2 wires on the IAC Valve
IAC Valve will close and RPMs should drop to 500, or engine may even stall, either is good it means no vacuum leaks.
If it stalls then look on the throttle linkage, you will see an anti-diesel screw, looks like an idle screw.
Turn it clockwise 1/2 turn, that will open throttle plate a bit more
Plug IAC back in and start engine
repeat test
Turn screw until engine doesn't stall and idles between 500-600, barely runs, NO HIGHER

That should prevent full stalling until you figure out why it is stalling

Clean IAC Valve
Working IAC Valve/computer should set approx. 1,100rpm idle when engine is cold, then it will slowly come down until engine/coolant is fully warmed up, and set "target" warm engine idle, 625-750, may be a bit higher in 1999 because of emissions regulations

 

[91stranger]

I will try what you mentioned. I have actually replaced the IAC, thermostat, ETC sensor and sender. Cleaned MAF and electrical connections. I have a new ignition coil and going to get new spark plugs in a few minutes actually. Also I have noticed my #27 fuse by the drivers door jamb keeps blowing. I only noticed this because I was towing my trailer and my overdrive wouldn't turn on. Replace the fuse and it came back on. Is there a reason for this fuse to blow constantly? I've replaced it about 4 times now in the last week. I'm at such a loss for diag because it doesn't stall all the time on command. I have noticed that it only stalls when the temp is up. I can drive to work and the gas station just fine (which is about a 25 minute drive). But when I'm leaving work it starts acting up. It will stall as quick as 2-3 minutes.

 

[RonD]

A bit of a contradiction there?

"I have noticed that it only stalls when the temp is up."
and
"But when I'm leaving work it starts acting up. It will stall as quick as 2-3 minutes. "

In my 1999 diagram it shows Fuse #27 in cab fuse panel powers OD control and Digital Transmission Range sensor(for automatics), Daylight running light module, and Pulse Vacuum if 4x4

 

[Big'Un]

Have you replaced the fuel filter ? I had a 96 Explorer Sport that did the same thing you talked about....let off the gas coming to a stop, and it would stall. Changed the fuel filter....never had the same issue.

 

[91stranger]

I haven't changed the filter yet. I want to change the filler neck first because rust keeps falling in. TO RonD, by temp I mean outside air temp. Mornings are still chilly here in Ohio but around 75-80 in the day. So when the outside temp is up it will stall quickly. Not every time though. Drove fine yesterday. Its so random. Seems like if I change the #27 fuse it happens more often. Going to take a lot of checking to figure out what is blowing that fuse. I will start with the basics like o/d wires and plug connectors.

 

[RonD]

Colder air is heavier than warmer air, i.e. "hot air rises" because it "floats" on the heavier colder air.

Gasoline engine's Air/fuel ratio of 14.7:1 is a WEIGHT ratio, 14.7 pounds of air to 1 pound of gasoline
14.7 grams of air to 1 gram of gasoline

This is why the 200mpg carb or "pre-vaporizers" were/are hooey

So with colder air computer needs to add more fuel, a liter of cold air weighs more.
You will have an air temp sensor with the MAF sensor, both of these compensate for air temp, MAF is a heated wire sensor, so the "heavier" and cooler the air the more it will cool the wire, and the cooling of that wire is how computer knows the air flow

If you can get your hands on a OBD Reader you could check out MAF for grams per second(g/s) flow at idle, at 700-800rpm on a 3.0l engine it should show 3.0-3.5g/s
Rule of thumb is 500rpms should be 1.0 g/s PER liter of displacement
so 3.0l engine would be 3 g/s art 500rpm, or approx. 3.4 g/s at 800rpm

 

[91stranger]

Colder air is heavier than warmer air, i.e. "hot air rises" because it "floats" on the heavier colder air.

Gasoline engine's Air/fuel ratio of 14.7:1 is a WEIGHT ratio, 14.7 pounds of air to 1 pound of gasoline
14.7 grams of air to 1 gram of gasoline

This is why the 200mpg carb or "pre-vaporizers" were/are hooey

So with colder air computer needs to add more fuel, a liter of cold air weighs more.
You will have an air temp sensor with the MAF sensor, both of these compensate for air temp, MAF is a heated wire sensor, so the "heavier" and cooler the air the more it will cool the wire, and the cooling of that wire is how computer knows the air flow

If you can get your hands on a OBD Reader you could check out MAF for grams per second(g/s) flow at idle, at 700-800rpm on a 3.0l engine it should show 3.0-3.5g/s
Rule of thumb is 500rpms should be 1.0 g/s PER liter of displacement
so 3.0l engine would be 3 g/s art 500rpm, or approx. 3.4 g/s at 800rpm

I have an OBD reader that I am borrowing from a friend and it can read live data. I did that and nothing seemed odd but I am not exactly sure what is wrong when reading it. Its not mine so I don't mess with it much. It never red flagged anything other than the p0445 code for large evap leak. I will have to check it and see what the data shows. anything else to check on the OBD reader for live data?