'96 winny rough idle when warm

this is a recent problem that our van has picked up. it runs great from a cold start. only when it has previously been running and has been warmed up does it idle rough. its rough both in and out of gear. and it only happens after initially starting it. stopping at a traffic light or something is fine. I dont think it has ever stalled, but it feels like it sometimes.

I should also add that just a week or so ago it shredded the serpentine belt. had it replaced and the garage also had to replace part of the idler or tensioner pully (forget which, sry).

It's probably your EGR ports that need cleaning. By removing your upper intake manifold (or plenum) you will get access to them.

There is a TSB for a NON-START condition after a "heat soak".
Basically, you have been running the van, and stop the engine for about 15 minutes, you come back to start the engine...and it will not start.
The cause is moisture in the fuel pump relay...which is inside the CCRM (Constant Control Relay Module) on the '96. Later, I don't know what year, they moved that relay into the power distribution box in the engine compartment.

The solution was to replace the CCRM with an improved one, with better sealed relays. The CCRM is located in between the battery and the radiator.
I have pictures of this in my pictures at http://community.webshots.com/album/201931518cScpNK

I don't know if this can also cause the rough running engine under the same conditions....but possible. I have had the same issue as you....and it has not done it at all this winter....but what fixed it?.... I don't know.

Another possiblility is a coolant leak, on the 96 the head gasket is not as high of a failure item as the '95. The lower intake manifold gaskets can leak....permiting coolant into the intake.
If you are loosing coolant (monitor the overflow bottle), then I would check into this (I put Bar's Stop Leak into the radiator to solve my several slight leaks, timing cover and lower intake manifold gaskets).
If you are not loosing coolant, then don't worry about this possibility.

You might also verify that the coolant level in the radiator (make sure there is coolant in the upper radiator hose...which you can tell by squeezing it gently). Just to be sure that the overflow bottle is still in the loop....
I noted that there was no clamp on the overflow bottle hose...where it connects to the radiator......and, while it was not an issue....I found that it was kind of loose. Also, only takes a little bit of something on the cap seal or where the cap seal seats.....to cause the radiator cap to not hold pressure.......simple wipe off solves that.

couple of updates.

1) no sign of any coolant related issues (no loss of coolant, no abnormal colored smoke, temp guage in the green)
2) just got the van back from the garage today after getting a tuneup done since it needed one badly. had plugs changed and oil changed primarily. they also checked the o2 sensor as that was one possible solution that crossed my mind and they said it was fine.

The only other thing that I can personally think of is the MAF sensor as noted in the "excessive fuel usage" thread. It has yet to be checked.

ok. after some research I think I have narrowed it down to the EGR ports.

1) the garage also pulled some emissions related codes from the computer.
2) a google search brought up someone else with the exact same problem of a rough idle on a warm start and he was told twice to check the EGR ports.

ok. turns out its going to be a different issue (possibly. at this point im not totally sure what IS the problem). the mechanic at where my mom works (for reference she is a bus driver and the bus garage is right there where she works.) took a look at it and put it on the computer and the specific code it read dealt with the IMRC. looked up the IMRC on here and it turns out to be the EXACT same symptoms we are having now. below-average gas mileage, rough idle, seemingly fine when moving. He found a clip missing off this IMRC thing and put some kind of makeshift replacement on. Havent had a chance to see if its helped any but I will let you all know of what develops.

Also, my mom just stopped for her lunch break and she says that the CEL hasnt been on all day and that thing has been on for as long as I can remember.