I have had trouble with my truck for a long time now about 2 months.  When
cold it would stall and run like it wasn't getting enough gas.  I talked
with a friend of mine about it and he said to replace my o2 sensor.  I did
that and had no effect but today I finally got a trouble code from the
computer telling me that the exhaust was running lean.  After looking into
it I have found several different things about my truck and the o2 sensors
some saying I have two sensors others saying four and others saying one.  I
could only find one right before the cat.  So my question is do you guys
have any idea what the problem is and what is the deal with my o2 sensors?
How many do I have and where are they?

Justin