86 B2000 intermittent idle issue - dies

86 B2000 Ext Cab, 5-speed. 203k miles, but runs great. It starts up and idles as it should, drives fine, with no misses.
I noticed that it will intermittently just completely die, whether idling, or when I come to a stop in traffic. If I drive it at highway speeds for a while, it seems fine right after I come to a stop, but then will inevitably start doing this.
Not sure if this electrical or fuel yet, but need to find the problem, as I need to sell this truck with minimal cost to repair.
Areas I should look at first?

Thanks!

Jack

check for vacum leaks. especialy on the bump up idol sensor. sounds like when u hit ur brakes it drags on the motor too much for idol. does it ever die while your going down the road with ur foot on the gas. if so it may be somthin else

Check the operation of the EGR valve; make sure that its valve completely seals, as it should at idle/low speeds.

You'll need to remove the EGR to do this, three hex head screws (10mm socket) on B2200, don't know on B2000.

These can typically be cleaned and fixed, or a simple block-off plate made and used if you are not emission-checked (EGR helps with NOx).

I've got two working used B2200 EGR valves if they are the same as B2000 (don't know that).

theyre both the same for b20 n b22 (10mm). jus see if its clogged. if not, push the valve open and shut and see if air shoots in or out of the nipple to check the bladder. if the bladder is torn it will most likely have the same symptoms as if it was stuck open.

Well it just so happens that while driving down the freeway yesterday, the EGR light came on. At first I was worried, but then read in the owners manual that it's set to come on every 60k miles.
Given the issues, I'll yank it off and check/clean it.

Also, I thought perhaps it was a vacuum leak, given that when it starts doing this, it's at idle, or as I come to a stop at a traffic light, but depressing the brakes several times in a row seems to have no effect, plus there are times that it's perfectly fine at idle, brakes or not.
I'm kind of leaning towards electrical, maybe the ICM, after doing some reading, but I'll first check the EGR. The ISM isn't the cheapest, and I'm trying to not put any more money into the truck, so I can make at least $100 selling it.

Mazda calls that the Malfunction Indicator Light, and yes, it is set to to on at 60K, 80K, 120K, etc. on the odometer. I think it's a way they can get you to come in and then they try to sell stuff like timing belt change, etc.

Anyway, there's two wires under the dash, at the extreme driver side, look up from underneath. You see one is plugged in, and one isn't, so just swap them. Do this every 60K miles.

Well, I found this vacuum diagram, which is for the 2200. Mine looks fairly intact, and all the lines are hooked up, and it's somewhat different.

It seems that what this diagram calls the Idle-Up Solenoid, may be bad, and intermittently working.
What I did was disconnect it, and no change. I then sucked on the line going to the Servo Diaphram, and it idled normally.
Until I get a new one, I simply bypassed the solenoid. It now idles, just too high, but good enough to drive it without it dying.

Odd that I have this, and have a manual transmission.

Idleup circuit - compensates when the AC is on.

just turn ur idol screw down a turn or too till you get a nother one. thats what i did and actually i still havent gotten a new one. it was bad on both my trucks lol. hope it solves ur problem tho good luck to u

Yeah, I think you may be right. Why else would you need to idle it up? I'm really hoping it's something other than the $50 ICM or the $ridiculous solenoid inside the carb.

Think I'll run some Seafoam through it and see if it helps.