i’ve noticed i have a hissing sound when driving that goes away with braking. my brakes work fine so i haven’t really worried about it but as brakes are important i figured i should investigate it. i pumped up the brakes and then started the truck. the pedal got easier to push so the brake booster is working at least somewhat. next was to see if the engine ran differently after taking the vacuum line off and also listen for a rush of air taking when taking it off. no rush of air was heard and the engine didn’t run any different. when i plugged the vacuum line the engine almost stalled. looks like i tuned it to run with a vacuum leak

. guess i’ll need a new booster. looks like city racer to the rescue once again!!