Overboosting help

I have a 98 jetta ahu and the higher I Rev it the more boost it pushes like when I first got the car it ran 13 and now at 3 grand it's pushing 20 and keeps climbing not sure what it is help

I would check the waste gate actuator. They're a known common problem. They will stick, sometimes open, in your case closed, and it hinders or completely eliminates its ability to hold a constant boost. If I let my car sit for more than a couple weeks, it will do real screwy things when I take it for a drive, as mine tends to stick as well. Sometimes lubricating it will help, otherwise it's like $400 for a new OEM one, or $600 for a new turbo entirely. This is just off of my own brief research, someone else might be able to chime in with better advice.

I've seen them do that.

Actuate them with a bike or Mity-Vac pump and lube the actuator at the same time, just don't go much above 20 psi. Use a penetrant to start, then flush it out and let dry, then use a graphite lube and work it in. The graphite will handle the high heat whereas the penetrant will burn down to a sticky mess and not solve the problem.

If your actuator moves between 8-12 psi then your problem is in the control system, but you should be throwing it into limp mode by that point.

could be the wastegate itself. Mine was frozen closed. Didn't know it was a problem until I replaced the turbo for an unrelated issue. Wastegate now works (I can hear it open) and my overboosting went away. That would probably be an extreme case but not to be completely ruled out. Check the actuator first. My actuator wouldn't move the waste gate so that's an easy check.