rob97TA

ok, i searched, but nothing really came up with my same problems. my 97 t/a recently has started idling pretty rough, not really rough, but rough enough to notice it. I got rid of the optispark, with ltcc kit, and new wires and plugs, so I know thats not my problem, and it runs great at upper rpm's and WOT, no misses at all. It pops a little through the exhaust like a small backfire, and it pops an intermittent (sp?) multpiple cylinder misfire and misfire #2 cylinder. I cant figure out anything. And also something I noticed a little weird i guess, is I gutted the cats and it never has popped a catylist insufficient, or w/e, code, like the cats are working fine. I havent had time to drive it and look at what the oxygen sensors are doing, but I did seafoam it a little while back before I did the plugs. Any suggestions or thoughts besides checking the 02's?