95 F150 4.9 Straight 6 Standard Trans Rough Start/Rough Idle HELP!
 

Hey everyone!

I am new here and I come to you in a time of need. I have been working on this truck since I bought her( truck from NV, stored winters in MN for 4 years until I bought it in Feb of 2019) and I continue to have this strange issue:
When I fire up the truck it will take a turn or two to fire and then will start, idle fine for about 30sec, and then it happens...
The truck will bog way down, almost to the point of dying and then kick back up to a low idle speed. (No Tach so can't give exact RPMs)
It will continue to bog down, just about to die, then idle back up. This goes on for about a minute and then it will catch and idle fine.
All the while, the check engine light is on but once it catches and idles and runs as it should the CE turns off.
Also, while this is happening, the truck responds to the throttle as it should but it sounds like it is at a lower RPM than it should be cause if my foot is on the gas when the problem goes away, the truck revs up higher.

It is getting worse now and will do the same damn thing 5 min later while driving. Or again after being idle for 2-3 minutes.
This seems to happen more often after it rains, snow melts, or when the truck is damp. Minnesota weather. Classic.

So, that is the issue.

What I have done:
Plenty of gas.
Distributor cap, Rotor, Plugs and Wires, Ignition Coil and Wiring, MAP sensor, vacuum line to the TAD, starter relay(mechanical fender mounted) and starter.
I did the starter and relay because I killed the original starter two days ago cause the truck would not fire.
After I installed the new starter, she fired up just fine but then after running the Key On Engine On test(EEC IV) the same issue happened again.
I am getting no codes listed except for knock sensor.
I will be happy to give anymore info and explain what I have done in further detail and I would love any ideas.

I am not trying to shotgun parts but I know that this truck is in need of love and I am replacing parts as I see the need but this issue with idle is a real noggin knocker.
I am going to check the fuel filter tomorrow.

Today she did not want to fire at all caused it rained all day. It took about 30min till it finally sparked. Then it did the same damn thing.
Plenty of gas.
Battery is more than happy.
Grease on every plug and wire.

Y'all have helped me a bunch and I have read many threads to try and find another poor soul like me but I figure it is time to reach out.

She is a beauty of a truck and I'll get some pictures up for y'all if you want.

If it won't spark, sounds like the ignition module or the pickup coil is possibly going out.

Replace the knock sensor if it's coding on you.

I'd suspect a dirty IAC.

Thanks for the reply and I'll check that out in the morning too.
I had that on the list to check but I skipped over it after seeing a pile of codes that needed to be checked off.
The knock sensor just showed up after replacing the starter and has been added to the list as well.

Should I just replace the IAC or can it be cleaned/repaired?

Cleaning may or may not help. If you want to try, remove it and use WD-40, work the plunger till it moves freely. If you replace it, use a Motorcraft part.

Here is the update:
I went out to work on the truck and tried to fire it up first. Nothing. Engine cranked but she wouldn't fire. So I spent the day diagnosing it.
For some odd reason, I couldn't get the self test to work(how I was reading codes). Weird.
I replaced the IAC today with a brand new one(I took the old one off and cleaned it out but didn't soak it cause it is electrical) and she fired right up.
It still wanted to bog down, doing the same as I mentioned in OP, but she started to idle fine after about a minute.
I shut it off, turned it back on, and did that three more times.
Let it rest and got cleaned up.
Came back out about 2 hours later and fired it up. Started just fine but did the same damn thing for about a minute than idled right.
Drove it for about 10 miles, got gas, and drove home. All surface streets so lots of stops and starts.
Now she is running like a top.
Tomorrow I plan to take her through her paces and cruise for at least an hour or so on the freeway and surface roads.
I'll let you all know more after that.

glc, thank you for the quick suggestion and apparent answer to my issue.