I've got a couple days, & about 100 miles, on this foil-fix.
It also fixed some power-surging I was getting at full throttle.
Originally, the TB Extension Cable was routed across the engine -> hidden down under.
During the p1239 codes, I had already plugged, & unplugged this cable for connection problems. I never re-routed it.
So, it was either moving it up above the engine, or foil-wrapping, & grounding the wrap that has helped it.
A third possibility is that Z's just respond well to Bling !! They also respond well to a 40 lb. Bag of dog food in the back.
I called Stillen yesterday to price 2 TB gaskets & a new TB ext. cable.
They requested my trouble code & a picture of the cable I needed.
Maybe I will hear from them today about the 'price'.