High Idle. Cleaned IAC, throttle body etc.

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AS the title states i'm still getting a high idle, about 1,200 rpms, even after cleaning the IAC, it's chamber in the TB, the rest of the TB, and whatever i could in the intake mani. The idle seems to stick at 1,200 rpms while I'm cruising and take it out of gear. The idle stays like that in neutral until i stop. I dont understand this. It is like the car thinks it is in gear or something when it is not.

Can a bad or clogged cat be a culprit of this problem? This problem used to happen on cold starts or with the engine running cold which I understand is normal, both when the car was stock and when I went catless. But the problem is constant now. I have the stock headers and cat on the car.

My stock exhaust was in my basement when my house flooded. It was completely submerged. I put it on the car a few weeks after the flood to pass emissions. It did not look clogged, and it was dry inside. I had no problems with the car and I passed emissions, but then got a cel sometime later while driving on the highway. After that, the car started idling bad. Im getting codes for the cat (P0420), and a few others for high idle etc.

My question then is can this be a problem caused by a bad cat? Can the cat be tripping up the rest of the system causing a high idle for a seconds? Should I try putting on my after market exhaust and see what happens?

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[Crawford Support]

Was the car retuned when you went catless and then again when you put the stock exhaust back on?

Crawford Performance