[dhunt00073]

Nobody seems to be able to figure out what’s wrong with my 05 w/t 3.5 L Colorado, it is hesitant to accelerate, and shakes above 45 mph, and barely moves when less thank a quarter tank of gas..

code: p0171
Repairs done:
Air filter
Fuel filter
O2 sensor
Spark plugs
Oil change
MAF sensor

what could be the cause?

 

[cart7881]

Welcome to the Nation.

If the problem ONLY happens with the fuel level below 1/4 tank and the only code that is setting is a P0171, it sounds like a fuel supply problem. When this conditions happens, have the fuel pressure checked. If you have a capable scan tool watch the fuel trims before and while this problem is occurring. Some scan tools will read fuel pressure.