I'm beginning to wonder if there isn't a mechanical problem. Like maybe the hard acceleration broke a rocker arm, stuck a lifter, popped a head gasket. These are all just possibilities that haven't seemed to have been discussed. At this point I think your on a goose chase with any kind of air leaks. Seems as though between you and the shops the air flow situation seems normal enough to run well. That's why I'm leaning towards something mechanical that may have been weak already and that accel was enough stress.
Might be a good idea to pull the plugs and see what they look like. Maybe check compression while you there.