98 2.5L misfire at low RPMs

[metolent]

Hi all - I've been searching around, but haven't found an exact description of what I'm experiencing. I have a '98 2.5L that seems to be misfiring at low RPMs. It's happening more regularly (well, over the last two days). No CEL is coming on and it stops as soon as the RPMs increase. Moreover, it's a bit intermittent as it doesn't do it every time at low RPM, but it does seem to be getting worse. At higher RPMs, it's fine.

I changed the plugs and oil tubes about two years ago, but didn't change the coil-packs. Thoughts?

thanks,
matt