might be on to something with the vacuum lines.
I was poking around under the hood and saw a single vacuum line that "forks" into 2 line and hooks onto the top of the engine right on top of the throttle body?. that line was clearly checked and dryrotted. I took it off (to get some new line) and it made no difference to how the engine ran. While under the hood, I got looking around and started experimenting. (for better or worse). I saw a couple of vacuum lines that went into a round metal can looking thing directly behind the battery. when I unhooked those, the engine idle actually increased. I decided to leave those off to see how it ran.
I haven't been "stall free", but I'd say it has ran a little better on the whole.

questions,
what might that mean is wrong and , what does that cannister actually do.?
also I noticed a rectangular box looking thing almost hooked to the side of the battery, but below the battery. It seemed to have vacuum lines going into it and had a couple of removeable caps on the top of it.
what is that and what does it do?

when you're not a mechanic, it's kind of amazing all the things you start noticing when you start poking around.
I understand the basic theory of the internal combustion engine, but all this extra stuff is not "up my alley".
thanks

 

When I unhook some of my vacuum lines the idle increases a lot. It's not how you should fix your stalling problem. The coffee can is a vacuum canister, it holds vacuum for when the engine doesn't supply enough. The rectangular box is the vapor canister. It takes gas vapor from the fuel tanks and filters it or sends it to the throttle body to be burned.

 

+1 -- if you unhook a vacuum line and it makes no difference, it's probably cracked, has a hole in it, etc. and should be replaced. If you unhook it and the idle ramps up, it was holding vacuum and should be put back in place.

You can also get a can of staring fluid and spray all of your vacuum lines and fittings (while the engine is idling) - as you spray them, listen to the engine - if it changes, you've got a leak. If nothing happens it's ok.

The elbow that connects to the MAP is flexible rubber, and gets pretty crusty over time. Check that one for sure since you're getting a MAP code. Not sure which 'fork' you found, since there are several. It could be one that's in the path of the EGR valve though. You might need to follow it to it's end and see what it connects to. Even if it's not a direct line, it could have some effect on overall performance and vacuum.

 

The "fork" in question comes from the vapor canister and goes to each side of the dual throttle body. It's where the fuel vapors are directed to be burned.

 

It's been a while (I apologize for that), but here's an update.

I replaced some of the vacuum lines and the truck actually has been running well. The stalling/idle issues have virtually vanished.
....BUT.....

now I'm having a new problem that I've never had before.

the truck will not start at all anymore if it is below freezing outside (truck sits outside all the time). It wont do anything but crank.

as soon as the temperature gets above freezing, it will start and run just fine.

Ive run virtually all the gas out of it, put fresh in, put "gas line antifreeze" in the tank with the fresh gas and it's made no difference. Do I just need to really "overdose" the tank with that stuff to be sure?
I think it may be something else because I've also sprayed starting fluid right into the throttle body and can't get it to even sputter. all it will do is crank and crank.
once it gets above freezing outside...bingo...it starts up with no hesitation.


Is there anything in the ignition system that would be temperature sensitive??

 

Well, at first I was thinking fuel problem until you said you tried starting fluid. So it probably isn't getting spark. Many of the ignition components are temperature sensitive when they go bad but usually they work when cold but not when hot. Testing them may not be helpful either since they work fine when warm, but I would have the ignition module tested anyways. It's on the side of the distributor and requires a special tool to remove. The tool looks like a **** with a small socket on it, a regular socket won't work because it won't fit in the hole. It should be in the tool aisle of the parts store. You can test the coil too but try to do it when it is cold.

 

Im going to operate under the premise "there are no dumb questions", so...
How do you test the ignition module and/or the coil?
thanks