another thing that i've seen this in the shop on cars with built up motors, is air intake tempature.... if you're taking air in right from the engine compartment, it can get hot enough to make the computer give a lean condition... if this is the case, you can pipe your intake to suck from a cooler spot such as from under the motorhome or someplace else with moving air, if you do run it under the vehicle make sure it wont suck up water when it rains.... a cold air intake is one thing the rice boys have right.... but even then we had it before they did... its called a hoodscoop