Hi,

My xterra has developed a peculiar problem.  Whenever it rains it
starts to miss.  I start the car, everything seems to be fine.  As I
back out of parking spot, it starts to miss, badly. RPM drops every
1/2 second.  start to drive and it does get a bit more violent to the
point of the whole car shaking at the stop light.  After few miles
problem goes away right after "Service Engine Light" goes of 3 times.
Last time I've checked the codes it came up as knock sensor.

I was thinking of replacing knock sensor, but it's quite a project
since intake manifold has to come off along with bunch of other stuff
which doesn't seem like good idea just to try given the magnitude of
the procedure and not knowing whether it's the sensor that is at
fault.

This morning as I was going to work, same thing. So I pulled into a
gas station to see if any spark plug wires have cracks and shorting
out. Couldn't see any, however I have noticed small amount of mist on
the plug wire boots at the distributor cap.  Now there isn't even
enough water to get into a cap and cause miss, but I am thinking that
perhaps some connector in fuel, emission or ignition system is getting
water in and causes problems.  I am guessing if this is the case
connector would have to be located somewhere in the lower part of the
engine bay.

Anybody had this problem or have any suggestions on how I can trouble
shoot this?

Thanks,
Anton