Two months ago I purchased and 1999 Volkswagen Eurovan GLs v6. About a month after that the van turn off while waiting at a light. I put it back and park and it started right up with no problem. But since then when the air is running if I step on the gas petal to acelerate the air blow much harder till I let off the gas. Plus it seems not to be shifting as smoothly as it did and running a little ruffer than it did. It's hard to tell because I haven't had the van for that long. After talking to a friend, he seems to think it is some kind of a sensor problem. There is no engine light on but sometimes it seems like there is a different smell coming from the engine. How can I determine what the problem is? Is it a oxygen sensor or some kind of other sensor? Or maybe a entirely different problem?

First, is the check engine light on? It sounds to me like the engine is idling too low & stalling, perhaps this is affecting the charging system & causing the noticeable change in fan speed when you speed up the engine. Has the tranaxle been serviced?