I've had this lean condition for a while, and I haven't been able to find the cause of the problem. I've been shotgunning the cheaper parts, since many could use the change anyway, but still have not solved the problem.
I was talking to a fellow today, and he suggested adjusting by rotation my throttle position sensor a little bit so that the valve is not as far open as the computer would think it is, there by richening the mixture. It seems like the sort of thing that's just so crazy it could work, but things like that have a habit of backfiring on me, so I thought I'd run it by you guys.

 

Just a thought......have you pulled the codes for your vehicle? You may have some bad O2 sensors that tell the computer your vehicle is running rich there by leaning the fuel mixture.

 

Yeah, the O2 sensor was one that I've replaced.
The O2 sensor gave me an idea, though. Theoretically, when the O2 sensor quits, the computer plays it safe by running really rich. Maybe I could rig a switch to cut the sensor for when I'm passing people or climbing a long hill, and bring it back on line when normal driving resumes. That'd only work of course if the O2 sensor affected only the mixture and nothing else.