Chevrolet: Head gasket, engine shot or maybe o2 sensor, head gasket, cross count

Question
Hello,
Chevy S10 1996 4Cyl 2.2L 130000km. I recently noticed an exhaust leak turns out its the gasket between the manifold and the exhaust pipe.  Before I had a chance to fix it the enigine started shaking like crazy. I also notcied the o2 sensor at the front is damaged.  Changed the spark plugs noticed the first one barely  had a gap.  It reduced the shaking but not entirely and still lacked power.  

Brought it to the dealer this is the diagnostic;

scan for codes p0301 missfire cyl1, p0302 missfire cyl2 p1133 o2 sensor cross count B1, S1 too few missfire code-check for spark on 1&2 ok check compression Cyl 1 0psi Cyl2 25psi cyl3 125psi cyl4 150psi-engine will have to come appart possible head gasket.

I got a second opinion engine is shot.

I live up North close to Alaska and not to many places are available, I heard similar stories where it was the o2 sensor, whats your take on this?

Thx.

Carol Ann

Answer
 Carol ;
hi  I wonder if it is just the 02 sensor  or the map  or both. if the head gasket was bad  , it should run hot or over heat  or water in the oil.   did you check  all plugs. or replace them and gap the new plugs. and did you take a compression test on each cyld.  it might just be a sensor causing all of the trouble.  ok >>