So, I changed the tank installed a smaller one (this one came with the kit 320cc) and put pieces of sponge around it. It hardly touches the fuselage. Changed all the silicone tubes and removed the cowlling so I can see if things are going ok. At 8:00 this morning was down the field and tested it. Had the engine re-adjusted to normal good rich. And the miracle was done.
I made three 7 min. flights, no dead stick no everheating just normal engine running. Just on the last flight there was rain..... so packed and left. More testing tomorrow if weather ok.
I will still fly without the cowlling till Im sure that no more overheating is happening.
Now about the cowling, Im familiar with the concept os 1 air inlet - 2 outlet and this is the case with the particular cowling but still I think it will be wise to use a baffle and direct the airfolw exactly on the engine head.
As you can tell Im listening to advices and what I did was to listen to the recomendations from the replies I had .............

Thanks guys