I have an Asp pulley and just changed the Maf. My car was hesitant and had a code which said I was running too lean and when I clean off the maf it would go away for a little while then return, so I figured it had to be the maf. I bought a new one and the same problem exists. I haven't resent the ecu, but I don't think it will magically make it go away. It is okay when I don't give alot of pedal, only when I really give it alot and this happens in every gear. It just feels like the engine struggles to pick up speed. The plugs were changed recently also. Fuel filter also changed already. What else could it be if the code persists and hesitation doesn't go away? Could it be the sc going bad, I hope not?