Another Brake question, tearing my hair out

[centexan]

Evening folks. Having a bit of an issue with my brakes and was hoping I could get some insight from you. '89 v1500 Suburban. I felt it was time for an overhaul of the brake system. Had leaky rear wheel cylinders so replaced those, all soft hoses, new rear shoes, new front calipers and pads, new master cylinder and after trying to chase down the issue, new brake booster today.

Bench bled the new master cylinder, used compressor driven vacuum tool to bleed the air out of the lines, then bled them traditional way (numerous times to make sure we got the air out). When turned off, have firm, high pedal. Turn the truck on, pedal gets spongy and sinks. Replaced the brake booster and it's about the same, except the pedal doesn't rebound as quickly. When I press the pedal from inside the cab, the rear chamber in the master cylinder seems to either gurgle or spout brake fluid up into the cover and the brake booster seems to flex forward. Is that normal. We've spend 4 afternoons this weekend trying to figure it out. Thanks in advance for your help!