[vector1]

if you have a wideband it will tell you pretty easily what is going on, mine would show lean with similiar characteristics as yours--letting off the gas from above idle say at cruise the rpm's would drop and the o2 would go lean and and the idle rpm would drop below what it was set at, i don't know exactly the cause but here is what i did. try richening the idle, it doesn't take much, just a slot width of all the adjusting screws and see what happens, if better try a little more, not much. next would be to set the idle up slightly. if it is dying under braking it is probably going rich, in that case drop the rear floats an adjuster flat at a time till it goes away.