Man, do I need help....

I have had an engine light on for a while that reads 25 (engine lean). At first it was on a lot and would some times turn off. When the light would turn off it was like an instant fix to the problem, but then it would turn on and be crappy again. Now it stays on all the time and it seems to be getting worse. Here are the symptoms when the light is on:

~ It idols real rough and has low RPM idol but eases up when in N.
~ It has serious loss of power at any RPM.
~ Though it claims to be running lean, it smells very rich and recently it has strated smelling like straight gas.
~ Of coarse because of the oder my MPG is around 12 when it used to be around 17.

What has been done recently:

~ I have had the head gasket replaced, but not sure if they did any valve cleaning or adjustments and that shop is no longer open.
~ New O2 sensor installed, but it has never ran well since it was replaced.
~ Oil weight changes from 10w30 to 30 and then back to 10w30 which ended up making it lose about 1 quart per 750 miles. Now I am back at 30 and don't lose any oil. (BTW does anyone know if Castrol 30 has any detergent?)
~ I had a couple mechanics tell me compresion tests came back OK, but I have not tried it myself.

I have had some suggestions to fuel injectors and valves, but what stumps me is why does my engine think it is running lean? You could run a engine on my fumes it smells so much like gas. I have had the sulfur smell for about a year, but I am attributing that to an orginal mufler with 180,000 on it. I need my truck back soon and as I fear it is getting worse. I have time this weekend to poke and prod, but I have no idea where to begin.

Ted
1995 4x4 4Runner
V6 3.0L