I had slight power brake issues but recurved the dizzy to have all in by 2000 and idle at 1000 in gear and mine was fine but you could not pump the brakes coming to a stop or you used up all your vacuum. then I used a 533 320 duration still had brakes idle around 1200 in gear then an ultradyne solid 263/271 @ .050 same thing now a roller 272/282 @ .050 .696/.717 lift still run the power brakes and idle in gear 1200 to 1300??