I have a bone stock 1990 3.9 2x4, I ran out of gas a few weeks ago and after filling it back up it started stumbling a little like it had water or something picked up from the bottom of the tank. I changed the fuel filter and it didn't make a difference, before that tank was done it got a little worse. I added a can of heet when I filled up next but still no improvement, again maybe a little worse. I filled up the next tank and again added heet and it's just not helping. I added seafoam in the next tank which I am running now and it's considerably worse. I again changed filter and nothing. Replaced dist cap thinking perhaps small crack allowing moisture in with no difference.
I have been paying close attention and I have noticed it is directly related to the outside weather, when it was raining it was real bad, and now tht we are getting cooler weather it's horrible. Last night was 45 degrees and I couldn't drive it to work, as the day warms up it gets better, but as soon as temp starts dropping it goes to crap again.
I went to local shop and talked to him and he said if he was going to replace something it would be MAP sensor. I have been searching here for a while and I found the post about IAC in FAQ section. If I had to describe problem it like it's struggling to get good fuel, like it's contaminated with water. Both fuel filters had nothing in them but good clean gas. Any help or suggestions? I can't afford a shop but right now I can't even drive it to work.

Update... I pulled the IAC off and took it apart, it looks new, no dirt or corrosion at all. I reassembled and problem still there.

 

did you try checking codes?

 

No codes

 

No codes or no CEL? Doubt it's the MAP sensor, but who knows. I'm not a big fan of seafoam, Lucas is a better bet. I've heard lots of horror stories when using seafoam on older vehicles. Fuel pressure regulator???

 

No cel, and No codes using the ignition on/off method to check.

 

Maybe you burnt up the pump by letting run dry. That overheats it and can kill the bearings ect. Check your fuel pressure.

 

You have the TBI injection on your truck with the injectors in top of the TB. Sounds like you may have picked up some trash from the bottom of the tank and it's got the injectors clogged up. May have to replace them.

 

Ok, been checking and reading all day and this is what I found. Todays weather is rain off and on and 75 degrees, when truck is running with breather off, I can actually see fuel spray going into throttle body. It's not consistant even spray, it looks like it's spitting uneven into the tb. So I have eliminated it to that point. Guess when I ran out of gas maybe it sucked garbage into injectors, not sure why weather affects it but at least now I have a starting point. Injectors are priey!!! $108 a piece.

 

You need to spend a little time on ebay. http://www.ebay.com/itm/REMANUFACTUR...sories&vxp=mtr

 

I'd try lucas injector cleaner first. It's only ten bucks. You can't over treat. Squirt a bunch in the tank.