trouble code p0171 on 00 4.7L
 

Well I finally have a problem with my 00 Dak. P0171-fuel trim lean bank one. The truck is running way rich though. I had a few p0200 codes pop up because of it. So, I think it may be a vaccuum leak, but I cant find anything with a can of carb spray... anyone have this experience yet? I cleared the codes once and only the p0171 came back, but its still running rich.

Time to change the 1/1 O2 sensor. It is throwing a false reading of a lean fuel mix. The computer is getting that reading and richening up the mix. Since you did not have a lean mix to begin with, you now have a very rich mix. The 1/1 sensor is located on teh exhaust manifold under the driver side of the vehicle.

I would say look into your O2 sensors. I had to unplugg one while doing a different test on my truck and I got that code while the sensor was out, but it went away with the sensor back in. You probably have one before and after your cat.