brake problems

I was putting a lift on my 85 xj and i had to remove the brake booster. I cant build pressure on the brakes. Ive bled all the brakes twice. When i try to pump the engine dies down like its a vacuum leak. I've checked all the lines, but i can't find it. Does anyone have any suggestions on what to do? Thanks.

You may have to remove the booster again and "prime" it. Do a search on master cylinder installation and the proceedure always comes up. Its called "bench bleeding" I believe.

The fluid is going through the brake system fine. I don't think bench bleeding would help it. I only lose brake pressure when i start the engine. Thanks though. Any other suggestions?

I heard it may be the brake booster or master cylinder. Any thougths on that, or any other ideas?