Weird smell on high rpm s

[Dino Dino Bambino]

Avoid fuel with ethanol

That might be almost impossible since European blends of gasoline usually contain 10% ethanol as an octane booster.

 

[patriotu]

So, i did check the PCV, all good, i did an ecu test for the engine and no code. The o2 good, the air-fuel mix good. I did check the exhaust front to rear.
But i also upgrade the gas and turn off the AC. And no smell. I ran the car on high rpm s like i always do and ALL GOOD. The bad smell is gone!!
Now i have to figure wich is who
I also upgraded with Hurst comp shifter and its a great improvment over stock. The look is great and shiffting thru gears its more fun. But i have a rattle between 2.8 and 3,5 rpms. Have any ideeas how to get rid of it ?
Thanks, Dan.