So I was driving home to my mom's house and at the beginning of my 4.5 hour drive, I found that my car was overboosting. WAY overboosting.
Normally when I go into the boost, it stops before 3 o clock. Today, it would spike up to about 5 o clock, which is BEYOND the yellow band.
Needless to say, I was very careful driving.
I also noticed it doing the following:
When driving with a steady foot near the boost range, the car would creep into the boost, then creep back to vacuum, then repeat in a cyclical pattern.
When boosting to go up a hill or whatever, the boost would spike (if I was careful to not overboost) and then come back down. For example, it would reach up to 4 o clock and then drop down to 1 o clock on its own. (The car's power would also trail off)

What I thought was that I had blown a hole in my CBV diaphragm. I'm running a Mitsu TD04 turbo. The CBV is separate from the turbo and is fed by a separate pressure/vacuum hose (the hose is attached to the turbo directly by what looks like a rubber vacuum hose covered with braided fabric).
I stopped twice - once for gas, and once to check things out. After I checked them out, the car stopped over-boosting.... for a while. Once I had been driving about 15-20 minutes, it was doing it again.

Anyone, please give me suggestions on what to check for. Everything's hot right now and I'm gonna eat dinner. I can check it out tonight or tomorrow, but it's traveling season and I'm supposed to drive.
I'm thinking check for vacuum leaks, check for the hoses feeding the turbo to be old and crackly (they're maybe 3 years old at most), see if I can move the CBV actuator rod myself.
I don't understand how the car can be doing this. Maybe the hoses heat up and that one particular hose (fabric covered and turbo to CBV), which I DID NOT replace is bloating and leaking boost. Or the diaphragm is leaking and once it hits a high enough pressure, it's enough to open the CBV some. It also seems heat related.
Maybe some kludge is built up around the CBV and sticking it shut until the turbo hits a higher boost.
Maybe the CBV is completely stuck shut for whatever reason, and the car is retarding the timing - causing the drop in power and a connected drop in boost - ie the car loses power so the boost drops, not vice a versa.

ARGH. help.
Dinner.
Will
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1990 740 Turbo, on its way to stock specs, maybe beyond