[s-cars] Knock Sensors?

[D Cosby]

Bill,

Once you try a higher octane fuel (or a bunch of octane booster / toluene) 
to eliminate that avenue, check the torque on the knock sensors. Apparently 
they can loosen and become overly sensitive.

Was talking to a mechanic friend a few years ago about a similar problem... 
He was telling me about a really tricky customer car (think it was an Audi 
90) with a similar problem. After eliminating the obvious, it turned out 
that at a certain RPM there was a loose exhaust shield (or bracket?) that 
would rattle and be picked up by the knock sensor. Long shot but worth a 
look after all else fails.

Good luck.
Dwayne