I've replaced all possible hose connections, master switch and yellow pod in engine bay. Everything seems to be holding vacuum well. After it sets for maybe 15 minutes, it takes a few miles before the locks will work again while driving. I have read pump vacuum should be 22hg. I have 20. Will this make a big difference?

Thanks

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Brad
1981 300TD - daily driver
1963 Chevy II
2001 F-250 7.3 Power Stroke