Intermitant CEL P1538 IMRC code. ’98 3.8L

[atikovi]

The van has 115,000 miles and the check engine light will stay on for a few hundred miles and then go off for another few hundred miles before coming back on again. It will store a P1538 code for the IMRC system. Any suggestions what to check for? Right now the CEL is off. Most questions I've seen here dealing with IMRC relate to a CEL always on but my problem seems to be intermitant.

[wiswind]

You could check to see if the IMRC's move freely from the open to the closed position, and back.
They are held open by springs, and the vaccum pulls them closed.
Often, a lot of crud builds up on the butterflies, and could cause them to bind.
If they seem to catch between the open and closed position, the solution would be to remove the upper intake manifold and clean them....avoiding getting junk on down into the intake as much as possible.

You can also check the vaccum lines between the IMRC actuators and the back side of the upper intake manifold to make sure that they are secure, and not damaged.

After that, it is possible that one of the actuators is developing a leak and will at some point need replacing.