Hmmm, after everything that you've tried, I'm also leaning towards the wastegate, too. It's not a very common problem, but I guess it could happen. Which wastegate do you have? If you have a wastegate stronger than the 5psi unit, you might want to get the 5psi piece and just use your MBC to turn it to your target boost level of 7-8 psi. For instance, if you have a 10psi wastegate, you wouldn't be able to use the MBC to decrease the boost level to below 10psi. But then, let's say you have an 8 psi actuator (and it's fualty) and you set the MBC to 8psi, your boost level should still be at about 8psi. If this is what you've done, then I'd look very closely at your mbc/boost vac lines or hookup. Be patient and keep checkin

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Kon C

"Sometimes, a man has to do what a man has to do."