I have been dealing with pesky lean codes on both banks with my 07 tundra for the last 3 weeks. I will start by telling what happened prior to getting the lean codes. I had one mechanic replace the fuel pump. He ordered it straight from the dealer (it’s OEM) and he too believed they should have given him the whole module assembly which would have been over an $100 extra. After he completed replacing my fuel pump, my truck seemed ok at first and was accelerating better and all. I went to work the following day and when I got off, I noticed that it started cranking over several times before starting (extended crank). Then I went to the gas station and once it was full, it leaked some from the tank (only if you fill it up). I later ended up with codes p0441 and p0455.  I told the mechanic and he said he may not have connected the lines properly. I lost my trust in that person and had a more experienced mechanic to come and check behind. He pumped some of the fuel out, dropped the tank and noticed that it was leaking from the top seal and that the connections was loose. He fixed it and the codes went away. I drove it down the road a couple of miles and my dash lights came on. I used my blue driver and the codes were p0171 and p0174. The long term fuel trims are high in both banks. I have noticeable hesitation, fuel economy dropped, and reduced engine performance.  

I had the oxygen sensors , mass air flow sensor, and intake manifold gaskets (which definitely needed replacing). Mechanic checked everything out did a smoke test and saw no vacuum leaks. He’s believing that I’ll need to have the fuel pump replaced again, but this time the whole module including the gasket and not just the pump. Based on our observation, the LTFT remains high at idle and regardless of engine load. He believes there’s a fuel delivery problem and the extended crank persists. He didn’t see any issues with the fuel injectors.