Mystery? Not anymore... for about 95%
It looks like "prototype" of Corsa 01, built just after extinction of Corsa Thron series production, but before creating ovalised tubes for special EMC order (serial markings match it perfectly).
I found identical Deda stickers on Moser frames and...these tubes were not ovalised in their original version.
F+F MT is probably Frame+Fork (KV = Kader +Vork was used more often) and the painting code is "inverted" TM = Motorola code
You have a unique frame, it was nice to see it - thank you