I have a 2001 F-150 4.2l v6 single cab stepside 4x4. the truck has 172k on it. ive been having a problem with it hesitating off the line and also feels like its misfiring when at cruising speed running around 2200rpm. check engine light comes on a keeps saying different cylinder misfires. also sometime says too lean bank 1 or 2. ran all kinds of injector cleaners on it. had the injectors prfessionaly cleaned. complete tune up done twice. new cats on it 30k ago. even put a new coil pack on it. it also does it worse when its cold. very raely it will also hardly even drive until it has completely warmed up. it will drive like a couple cylinders are not firing at all. when this happens, it has no power and it i try to gun it, it will knock under the hood like crazy. other days it will drive like its brand new. most of the time it will just "skip beats" while cruising or while getting up to speed. when i gun it on these days, its got all the power i should have. any suggestions?