Rough idle from brake booster
 

I have a ‘81 f150 with a 300 straight six, runs great until I replaced my brake booster. Has very rough idle, sometimes hard to start. I checked all vacuum lines and no cracks/leaks. I then pulled the vacuum line off of the brake booster and instantly had perfect idle like before. Reattached the line and right back to rough idle. Wondering why? Faulty brake booster or is it something in the vacuum T.

Thanks in advance!!

Brake booster needs to be replaced.

that’s the only thing I could figure, must have been a faulty booster I got

So we know to stay away from where you purchased it, where it was it purchased?

I purchased it from carquest, I work for a mechanic shop and ordered it through the system we use for all our parts, typically never have problems but always is the few cases like such

Sometimes we have choices where to purchase , and a good part of the time they are Ok, but with the problem of "Imported Junk", it can affect the results we get.

Exactly, I think it must have just been a bad booster, I’ll update you if the new one fixes my problems