Code P0171 is driving me crazy. I installed the MD 5/16" iso thermal spacer along with stillen air box/z tube combo. I have pulled everything off and reinstall 3 times now and this effin code keeps popping back on every couple hundred miles. Absolutely everything I can see is tight to specs. I don't hear any leaks. Car runs perfect and strong. I've cleaned the MAF twice now too. Car also has coupe mid pipe and HR Y pipe. Can anyone help with some insight on Wtf I can do to solve this? Thanks

 

Almost forgot, car is a 2003.5 sedan 5at with 60k miles