So, it runs smooth. Has a bad bog and no power. Plus major brake fade. Hell to stop. 60 mile trip to the city and back. Still runs nice.
Before I completely F it up I'm bringing it to a friend that runs a shop.
Not our only transportation (two motorcycles and a 01 Ram) but definitely not the one I want down.

 

I can't see any correlation to brakes; unless you somehow disconnected the vacuum line from the brake booster to the manifold. That would cause the bog.

 

I've looked. But brake pedal gets hard as if no booster.
All I did originally was swap tensioner. You know how easy that is. That alone has brought on everything else. No vacuum leak found.
The brakes work fine when first started with codes clear then minutes later hard pedal. Disconnect battery, drive away, still bogs. Block away the light comes on and brakes fade.
Still have done no changes except tensioner.

 

Check the vacuum tube to the booster, it may have gotten jiggled or cracked.

There is NO other way that the brakes could be affected Except a coincidental failure. How about the check valve being loose or malfunctioning?

Somebody, not long ago, managed to crack the elbow on the intake manifold. We never heard how.