Ok, will limit boost to 10-12PSI by throttle.
How do I check:
The wastegate line? With air pressure, the turbo end should be open and the wastegate end should be closed until about 12PSI, then open, right?
The pressure switch on the intake? And what does it do exactly?
The overboost valve? It's supposed to cut off boost and let the ALDA drop to 0 PSI, right?

Thank you very much for the fast reply.

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I suggest we solve high gas prices with environmentalists... unfortunately they don't burn well.
1982 300CD, 220K miles: This vacuum system will be the death of me yet! (OBK #26)
1977 F150 400 C6 2wd, 10.2 sec 1/8 mile with 2.75 gears.
1965 Mustang. Mostly stock... LOL!
2001 Ram 2500, cummins, 5spd, 202k miles.(girlfriends)

The wastegate line is just a normal hose. Check to see if it's broken, cracked, soft, oil soaked or crimped closed. It may be worth a try to get some hose from a local auto store to try and see if it solves the problem.

The pressure switch on the intake is an electrical switch that connects the overboost ground circuit at 16psi. The overboost valve on the firewall is constantly fed positive voltage from the fusebox (Check it's fuse, BTW). At 16psi the switch connects it's ground and the valve actuates. It vents the boost signal going to the ALDA which cuts fuel down to safe levels. If it's working correctly, you should noticeably feel the engine's power cycle up and down on it's own as the ALDA gives and takes away fuel.