I hope this is the correct forum for a gas Class A, if not mods please move it. I recently purchased a 2005 31' Tiffin Allegro with the 496 Workhorse Vortec motor with a Banks header exhaust system installed. It was running rich at the time, I replaced the plugs, wires and heat shields. It still idles rich and is diesel like rich under load. I cannot see any O2 sensors in the system and hear rumors about a Mass Air Sensor that may be the issue. I don 't know where it is located, the part no., etc. There are no codes being thrown and no check engine light. Until I can locate a repair manual for this motor, can anybody pass along any ideas? Thanks!