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2001 Civic LX M/T no mods changed out IACV and upstream 02 sensors, did idle relearn ( pulled fuse and disconnected battery for 1/2 hour. reinserted fuse and jumpered positive and negative cables to drain capacitors checked TPS and voltages in range. After about 1/2 of driving the car will idel rough and try to stall out it comes and goes. Also have new plugs and coils all Denso parts and NKG plugs Any anyone have this issue and what was the fix-TIA

 
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Have you checked the fuel pump for consistent operation? Do you smell fuel inside the car?

 
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Any CEL codes? Smoke tested it for vacuum leaks? Cleaned the throttle body and butterfly (flap)?

 
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What brand iac and o2?

 
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Hello, thanks for the responses I have not checked the fuel pump no smell in the car. I have no other related fuel pump issues with it, as it starts fine but would not rule that out. So I am guessing I would need to check the fuel pressure. No CEL codes at all checked it 3 times, but no on the smoke test, I have not done that, correct me if I am thinking worong about this, but if it was a vacuum leak wouldn't I see it all the time? as this only happens after driving for a bit, but again I am open to anything. As no stone unturned, I cleaned the unit cleaner have not removed it, the IAC is Autozone and the o2 is Denso. I was thinking about a new throttle body of a donor from a junk yard but I worry I'll be getting the same issues (thoughts). Lastly, could it be CAT, however, if it was wouldn't I see more than a stall rough idel after running for a while? Just trying to get another 100,000 out of this car. Again thanks for the input

 
Rep Power: 223

Iac is probably junk, Hondas dont like aftermarket electronics. Try one from a junkyard, just clean it really well