So, my C6 is still acting like crap after a new vac pump and power brakes still aren't what they should be. They are better than before but it acts like it is having a problem recovering the vac pressure. Only the throttle/trans hose and brakes are hooked up to the distribution block. It does go from there->throttle->c6 correct? It could be a bad booster, but I'm thinking it's something else. I'm not braking while accelerating so there should be no load on the booster, but it's still acting like the trans isn't getting vacuum. Could a bad modular valve cause other vacuum problems, especially if its comstanly sucking air? This makes me think it could be the problem. Not my video, but that's not normal right? If one does this, I think it could definitely cause poor vac: Anyone had such an issue where the modular caused power brake problems? I can manually shift from D to 2 just fine. Going to D at a high enough RPM/speed keeps it in 2nd. If RPMs/speed is too low, it goes back into 1st. 3rd is VERY late, around 45mph I'd guess. My healthy F250 C6/vac shifts to third around 27mph.