Ok, here's something else to think about. The IP shutoff responds not only to vacuum from outside, but to a pressure buildup inside the crankcase. So if the CCV system is plugged it could cause the same symptoms.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References