Chevy & GMC Vans

unhooking it for like 2 -3 minutes ought to do it. costs nada. The ecm will reset to default settings and then start to relearn the system to try to bring it into equilibrium. Need to drive it some a varying speeds for it to re-learn.
Worth a try.

Is this still a problem?

I have learned a lot from my project van. I have found that if the throttle body is dirty (inside the bore including the throttle plate) this will block the "idle air" decreasing your idle. There is an idle adjustment screw (I don't advice doing and adjusting) under a sealed plate on the TBI on the same side as your throttle cam. You are supposed to have a very narrow gap between the throttle plate and the bore. You really can't inspect that unless it is off your truck. Just make sure it is clean in there.

This is a simple thing to check and resolve so give it a check out. THis is a wise thing to do for anyone. I got a can of seafoam and cleaned the bore and plate out until it was clean. the throttle plate on my wifes 98 (not tbi) also did this and it would stick a bit just off idle.

I believe teh IAC shuts completely in closed loop (when warm) It steps closed gradually on the coolant temp. If you turn the ac on it will increase the idle.

Once you do all the simple stuff, you could actually pull the TBI and perform a rebuild ($25.00 kit ). There are little screens on the injectors than can clogged with stuff, but I would first look at the injector spray pattern first as someone has said before. Then you can get the fuel line adapter to install a fuel gauge. You can get one from CFM tech or turbo city.

yes this is still a problem but i am gonna check a couple of things like ignition timing, map sensor, o2 sensor, and something else.

i also replaced the map sensor still no change

unbeilevable i did a tune up this evening and when i went to pull the coil to cap lead off i noticed the ignition coil was wabbling torqued it down and finished connecting the last wires took it for a test spin and was running perfectly if the whole problem was that damn coil not grounding properly i'm going to be pissed but works fine now

okay update: still have rough/low idle at stop lights, but i been pay more attenion to it lately and i have noticed that when cold i have lots of power but when warmed up it feels sluggest and when on the highway and i floor it i smeell a strong sulfur smell.

See the Red Headed Step Child Post. The sulfur smell and symptoms could be the cat clogging up at operating temp. The fuel system runs closed loop until warm and gradually relies on the O2 sensors to regulate after it warms up.
Hope this helps.
Phil

here is another update: i have not done much but spend more time with it i noticed that sometimes when i floor it it will boog down and after a couple seconds it will go fine it sounds like it gets plenty of air but not enogh fuel like the tps is not telling the computer to add more fuel i think that this is related to my low idle.