My car keeps tryin to run very lean ad i cannot figre out whats wrong and causing it, it threw a code sayin both banks are runnin lean so i went and got it hooked upto an autotap, it was addin 25% more fuel and 50% in the long term fuel trim it also picked up a slight occasioanl misfire. At first i thoight it could have been the hypertech tuning so i turned it back to stock and its still doin it. The o2's shoud be good because both are readin the same unless both are bad i dont see how. Its got a new fuel filter, o2 simms on the back functioning properly. Please help me this is really getting frustrating

 

You could have an exhaust leak somewhere before the 02's, so the car thinks it is running lean and it isn't, or it could be the maf or i've even heard the pcv could play a role in the car running lean.

good luck