cel p0171 and p0174
My CEL is on....again. Late last winter it came on for the first time. Codes read lean on both sides, P0171, P0174. Thought it might be the fuel filter since Missouri had just started putting ethanol in all gas. Worked for a couple of weeks but came back on. Tried the same thing again only the weather warmed up and it didn't come back on during the summer. Then last month it came back on. Seems that if temps are in the 30's and once the truck warms up the light comes on. I tried cleaning the MAF and the Idle Control Valve. Cleared the light but it's back on again after a couple of weeks. I did notice that it made the loud whining sound last summer that others have talked about when the Idle valve is not working properly. The truck runs fine, but the light keeps coming back. '98 Ranger with 4.0 V6, 145,000 miles. Thanks.