Recently had an idle problem on my 00 Civic EX. Ran up and down. Removed and cleaned the IACV. It fixed my idle problem but it has really poor acceleration and I'm only getting about 26 or 27 mpg. The car is an auto but doesnt run near as well as another I drove. Can the IACV still cause driveability problems? I've checked for vacuum leaks also.

 

if it is defective it does - but yours in now OK, no ?

how many miles since a tune-up?
is CEL on ??

check your timing.

set the tire pressure to the specs.

 

The idle is fine but driveability and mileage are poor. I work on cars for a living so I have covered the basics like tire pressure,plugs,fuel filter,cap and rotor. Still has awful acceleration and MPG. The cel is on and am getting a P0505 which is why I suspect the IACV