Rough Idle 2009 Honda Civic

[Garrett Stanton]

TLDR at bottom) Hello everyone one, I’m an aircraft technician and have a basic understanding of working on cars, I bought this car from a used car auction place and has 199k miles problem started after I replaced the egr valve and it struggled to maintain a good idle and if left on long enough will choke and the engine dies out, also doesn’t do it when it’s cold outside, I originally got misfire codes, so replaced the spark plugs and coils and it still idles rough, I gave up on it and decided to just not let it idle to prevent damage to the catalytic converter, because runs fine when going above 15mph, so if auto stop doesn’t engage I turn off the car at stop lights (I am aware it’s not the best solution especially since it’ll wear out the starter), it also chugs sometimes when I accelerate from stop, but I want to try and fix it now so if anyone has an idea let me know, so far I did a diagnostic test and it seems to be running air rich, and probably a fuel system issue, I don’t think it’s the fuel injector because it didn’t show a consistent misfire in the cylinders so I’m thinking it’s fuel pump but also read it could be the maf but the obd reader showed it working, and heard it could be the pcv, any direction would be awesome

TLDR
car idles rough only below 10-15mph, sometimes chugs from stop, when cold outside doesn’t idle rough, lean fuel/air mix, air rich

replaced the following:
EGR
Coils
Spark plugs

Thinking possible cause most to least:
Fuel pump
PCV
MAF

Topic