My 86 westy is running very rich with spark plugs becoming sooty after a
dozen miles or so resulting in a rough running engine and some black
smoke at the the exhaust. Compression is good , timing and idle at
specs.  tempsensor2 checks out although it is difficult to get a
reading. Replaced the idle stabilizer valve(it needed it}.  What are
some of the more logical  things to take a look at?  How does one check
out the oxygen sensor?  Any suggestions would be much appreciated.
Thaking your in advance,
Alex