So I’m pretty sure my vacuum booster died. Pedal is rock hard. Brakes barely work. Hissing sound when pushing the pedal. And had a high idle and rich CEL for the last two weeks that I was tracking down.

Real question is the replacement… advance has a wearever booster for like $450 (https://shop.advanceautoparts.com/p/wearever-vacuum-brake-booster-without-master-cylinder-53-2727/18690417) Amazon has a no name for $100 (https://a.co/d/8NqMX4U)

has anyone used an Amazon one? Timmy the tool man video is installing a knock-off.

 

I'd just double check the check valve (small pun?) isn't stuck shut. That seems to happen when they get old, especially when the weather gets colder. It's supposed to open to let the engine suck air out of the vac booster, then close when the throttle is open and there's no engine vac. When it's stuck shut no vac in the booster at all.

I replaced mine a few years ago. It started sticking in REALLY cold weather (like below 0 degrees), then it gradually started doing it more often at warmer temps.

I guess it's easy enough to test, just disconnect it from the booster and see if it sucks air in.