Had error code P0505 on 2000 Toyota Corolla Automatic 1.8 L 4 Cyl 173000. Changed Idle Control Valve. Check Engine Light went off, but came back on about an hour later. Have rechecked Codes. Still have P0505 code and P0171.
I believe the P0171 is because while running at idle I removed each injector electrical connection one at a time than replaced it before taking the next one off to see if one would sound different.
When cold the car hesitates badly when taking off. Once warm it runs good.