just got a 1995 jetta tdi   mainly to save on fuel money....running biodiesel....what a savings...anyways the car has some issues....engine light is on....reset computer and light comes back after short amount of driving....seems to run great until about 3000 rpm then it goes into limp mode.....any ideas or anyone point me in the right direction...don't know much about these yet but its like the turbo quits at 3000 rpm...also i have heard about hooking a laptop up and "tuning"   looking to get into this stuff for fun any help would be awesome  

The item to which you are referring for "laptop tuning" is called a Vag-com. You should be able to get one from several different VW performance sites, such as www.kermatdi.com. They're not too cheap initially, but once you've used it, it's paid for itself in diagnostic fees & labor costs saved. The engine light, well, the Vag-com can tell you about that. If you don't want to spend the money on a Vag-com, most of the code readers sold in auto parts stores will pull the engine codes, and you can look those up in a book or on the Internet. The turbo quitting at 3K RPM could be a host of things, from excessive soot buildup in the vanes on the exhaust side to a malfunctioning sensor or actuator. By the way, a great resource for how-tos and information on TDI-equipped vehicles (VW and others) is www.tdiclub.com.

Good luck with it!

Jim