I'm getting code 174 (lean bank 2, the adaptive fuel system has reached it's rich limit). A while back the engine started missing badly at WOT but rans fine otherwise. I changed the HEGO sensors, no difference. I cleaned the MAF sensor and that seemed to fix the problem so I cleared the code. After a couple of weeks the problem started again. The code came back so I changed the MAF sensor. Problem solved, or so I thought. It's been 3 months the engine is still running fine but the code came back. Any suggestions???