Power loss in corsa (Chevrolet, Opel)

Hello very good day, I am from Morelia Mich, Mexico I have a query to do and hopefully they can support me, it turns out that I have a 2004 Corsa that I try to keep very careful, I make its oil changes and affinations on time and the truth I have maintained my cart in very good condition but a few months ago (October 2012) I began to have some power problems with the car, as well as high gas consumption something like 8.5 km/lt, my mechanic did not Problem and I comment that I change cables of spark plugs temperature, oxygen sensors, in short, a lot of things .... In the end and why I asked him to change the distribution band because he already touched him, he found that the gear that goes in the crankshaft pulley was already sweep Being "chueca" and towards which the gear was sweep, at that time the pulley, gear and the dist., It feels again half "donkey" and with some "jaloneos" almost imperceptible when I make the first change at second speed, the consumption of gasoline again shot, when I turned it on in the morning or when it stays for a few hours without moving it tends to go out or "drowning" ... if for any reason in the city I find a slope is a problem up because the car has no power, in the same way when I started when I started when I started. Until after a while and grabs speed,

it should be noted that I have not taken it with the mechanic for revision but I am almost sure the fault returned since suddenly it is heard as a pounding that I had already heard when I had the initial failure in the area of ​​the distribution band apparently the pulley is loosening or something like that but I want to pregnant them, if it is something that can happen again with just a few months of new. Is there another factor that is making the failure come back? Or simply the mechanic is doing wrong when riding the pieces and synchronizing the band, etc? In fact, my mechanic told me that most likely, the crankshaft must be changed because he says has a kind of "game" with the gear or pulley, something like that! The truth is how much I know about the subject is because I have investigated in some online forums ..


I hope with your experience can guide me with possible solutions and guide


thank you !!