Water pump/Opti
let the car sit on idle and observe the engine as it reaches that temperature. rev it up some and see if you can find any coolant leaks.
ignition system:may not be getting enough spark!
ICM
COIL
OPTI
these are just possibilities,certainly worth checking out.has your mechanic hooked a scanner to it,bring it to AutoZone if you have one in your area they will scan it for you.good luck hope its something small

oh and the knock modules job is to read the data given from the knock sensor the module from the Lt4 is a little bit LESS sensative to avoid timing retard caused by false knock aka roller rockers and steel valve covers




