That may be my problem. My manifolds have been a source of irritation since... Forever. Passenger side has small leak. I have stacked 2 gaskets from the header to the exhaust pipe and I still have some exhaust noise. The driver side had one stud that I had to drill out and use a bolt and nut. Not ideal. In a very, very bad spot (on outside) . I'm pretty sure that my exhaust or the manifold on the passenger side just doesn't line up right. I'm afraid to tighten it too much because I have stripped and replaced studs before and I cringe at the thought of removing the manifold from the engine, having done so many times.

For the vac problem I should note that I have no brake assist for at least a minute after I start my truck, and I have a steep driveway! Then, approximately ten seconds later, I have good assist but when I use the brakes and released then use them again (car coming that I didn't see), there is no assist in the second press. I guess that can be a vac leak anywhere

 

This weekend I am putting on my new crank seal, water pump, front cover, and oil pan gasket, to solve numerous leaks. Basically, I see every fluid except transmission, brake, and diffs. All of this is weather and wife permitting. I will have the fan off so it will be a good time to put smoke everywhere.

Can anyone snap a picture or be real specific about where I should looks for vacuum leaks? I don't know anything about brakes beyond replacing the pads and bleeding the system.

Beside the point my 29 dollar eBay power steering pump is not happy, either, but the leak is slow at the moment. I need but won't get castor correction (for lift) and have wider tires, so replacing power steering pumps may just be part of the deal. Thanks for letting me vent

 

Check out YouTube for videos on how to do a smoke check on your vacuum system. I have used the cheap cigar method with good success before.

It sounds like you may have a collapsed booster line and may be worth replacing to see if it helps with your brake problem. Good Luck!