Have a 01 gt supercharged that is throwing P1131& PO135 lean. It has long tubes and no cats. It also sometimes seems to load up at low rpm. And occasionally has to be throttled to crank. I've replaced fuel filter and ran a couple cans if sea foam thru it. Could the lean reading cause this loading up because it's actually making it rich. I'm guessing with the long tubes it has to have o2 extenders could they be bad.