my setup is a 99 civic ex with a 00 b16a2 in it. the motor is 100% stock because i need to have it smogged.

the ecu recently threw a code 14 cel. i ran through some diagnostics regarding the iacv but couldnt find anything wrong. i then went and just bought a new iacv and dropped it in. the new unit worked fine for about 50 miles when all of a sudden the cel came back. i've checked the electrical connections also, and there are wires running where they should be. the only obvious change in the car's behavior is a sometimes increased idle (1500 rpms) and sometimes low-rpm stutter. both of these issues are transient, i.e. not present at all times. so, now i'm lost... i'm going to swap in another ecu and see what happens, but i'm not getting my hopes up.

any advice on what to look for or where to check would be greatly appreciated. thanks in advance.