Rep Power: 224

I discovered something really weird yesterday (2001 Civic EX). The idle was all over the place once warmed up so I replaced the IAC, this seemed to mostly fix the issue. When I slowed down for a stop sign though the idle would jump up to ~1500 rpm then drop to ~1000, then back up to ~1500, and finally drop to normal idle. I though maybe there was some air in the system still, I also had the loss of power issue discussed in another thread so I ignored the idle. While replacing the fuel filter/strainer I emptied the fuel tank down to about 1/4 tank. Afterwards I took the car for a 20 mile drive, no loss of power and the idle seemed to fix itself (no more wandering at stop signs).

Well yesterday I put a few gallons of gas in bringing it up to just shy of half a tank and the idle issue immediately appeared again as I was leaving the gas station, coincidence?? I really don't know what to make of that. The IAC I used came off another Civic that didn't have any idle problems but it had been sitting for a few months. I guess my next step would be pull it back off and try to clean it real well. Any other ideas?

 
Rep Power: 119

 
Rep Power: 224

One thing I should mention, when I had the gas fill cap off I noticed the rubber seal on it was broken. I swapped a known good cap on before I left for work this morning.