Problem with my v6 vortec spends a lot of gasoline

I need someone to help me find the fault to the S10 only give me 4km/l urgent !!!

Hey fortune tellers, we are not explaining the problem a little better to help you, there are there are tapes of reasons that can cause excessive consumption.-

Look when the engine is going to the second llavaso, the loago that lights is stable when accelerating normal accelerates does not rattle does not tremble but if the temperature rises up to a little more than half of the meter and the car feels heavy. another if I brake it and accelerate at the same time no longer size. Another somewhat strange aspect is that even with the cold engine he starts from walking about 500m siacaso uncovers the radiator and it releases a huge precion just like a car that is hot. something else? The net can help me that well and have me questions I will be easier for me

Check the exhaust tube, let out it and once it improves that and was the covered exhaust tube

the tube? or the catalyst?