How hard is it to fix this problem? It is a 2000 3.4L with 128km

This is what can go wrong.

[/URL][URL]http://www.automotiveforums.com/vbulletin/showthread.php?t=946194 (http://www.automotiveforums.com/vbulletin/showthread.php?t=946194&goto=newpost)

Other than that its all nuts and bolts.

Not hard realy, you just need to keep track of what goes where and get the torq specs right, they changed in 2003.
The only tricky part is the rocker arms when reassembling them.

Here is a link to a 3.4L prceedure with pics and stuff.
3400 V6 SFI LIM Gasket Procedure (http://www.automotiveforums.com/vbulletin/showthread.php?t=688030)(the chevy top 3.4 link)

If you have any other questions just ask. Done way to many of these over the years.

Thanks.