Intermittant Knock Sensor Warning, Connector Goes where?

[Larry C Leung]

Looking for collective list wisdom.

Patient '89 200Q MC2, chipped 1.8 bar

1.)    My car throws occasional knock sensor codes (USUALLY the same
sensor). I've checked the tightening torques and connector, and it still
throws intermittant 2142 codes. Do knock sensors normally fail
intermittantly or do they usually just go all at once. The sensor that
throws the code has never been replaced,
the other one has.

2)   Any ideas on why the car seems to stumble/balk/choke when the air is
cooler (around 30 to 35F and cooler, or 0 - 2 C and cooler) and runs fine
when it's warmer (though not always). Also, the car doesn't always drop
down to appropriate idle after ith has been run on the freeway for more
than say 5 minutes. Of course, it's intermittant again.

3) Found an unconnected connector along the wiring harness that runs
along the block. Can't find another end that it would appear to connect
to. White 2 pin standard VW connector, one brown, one black-brown and one
red-yellow wire run to the connector. Is this a tester connector, or is
there a potential problem. The length of the pig tail is such that the
other end MUST be towards the rear of the engine block.

Please reply directly as I'm on digest now.

TIA,

LL - NY