My truck started doing this yesterday it idles a lil high and when I press the brakes the idle goes up and down but only does it when I press the brakes..can anyone help? What do I do??

 

Brake booster is connected to vacuum, it may have a leak or accentuate another leak. That could definitely cause the idle to fluctuate.

 

I checked the hose and its not leaking??

 

Its leaking somewhere in the braking system. If your brakes are craptastic it's probably the booster itself.

 

Thanks guys I'll look into it tomorrow

 

Auto or 5 speed
if its an auto check your tps

 

Im guessing its EFI?

Ifso: Your idle is set too high... The surging is your ECU thinking your coming coming to a stop. When you apply the brakes the ECU kills the injectors to save fuel... Lower your idle and it should stop surging when brakes are applied.

 

NashMan its a 5speed...B.Y.E I'll adjust my idle thanks a lot its so annoying hearing it bounce up and down