So I've had some problems with my brakes I've been overlooking since they worked fine, but I decided to break the calipers down and paint them with some vht and replace the seals. Job took a few days and the front lines bled dry. I rebuilt everything, (Caliper piston boot retainer wasn't on either caliper or in the kits, listed on manual diagram tho?), bled just the front from inexperience and had my usual feeling brakes for a very little bit but then my pedal keeps going down all the way to the floor and is slow to return and remains spongy even with pumping. I have since flushed the system, replaced the 2 bleeders I wire wheeled, and fully bled the master cylinder and all the corners.
Running the car 2 minutes, depressing my foot to the floor, shutting off the engine, I can hold the pedal down 30 sec.
With engine off I can pump brakes and it's rock hard at 3 different levels for the 3 pumps until you reach the top of the pedal which is solid, minus about half an inch of play at the top.
Pedal slowly sinks to floor and slow to rebuild pressure still after flush and bleed
My guess from looking stuff up online is a check valve or line? I looked for a valve along the line but lose where the line goes behind the passenger side of the engine, but I can't find evidence of there being a check valve in the manual? Is it built into the booster? Where should I go from here? This testing was done on stands and without revving the engine at all too, would that affect results? Thanks in advance