braking problems

[civic123]

Well lads and lasies I recently bought a 97 1.4 civic and the brakes were grand when I first got it but the next day I put her on the lift and it was on it for 3 or so weeks. During this time I changed the spring and cv boots, and when I got into it and went to drive it the brake pedal went to the floor and I had to push very hard to find any braking power.When I pump the brakes aswel the engine revs go up and down when theres pressure built up . They can be grand sometime but if you drive a 100 metres with little or no acceleration they go again. I have changed the master cylinder and before i drove it the everything seemed normal but when i went on a proper test drive they went back to the same...

Dont know why this is happening but would appreciate any ideas or suggestions

[JohnnyG]

This sounds like a servo problem if the engine is revving and you have a hard pedal,Disconnect it after you leave the car running for a bit and see if you get a gush of air,if not you might have a broken diaphram in the servo.Check the pipes for cracks,also check the pipe where it goes into the servo to see if you have vacuum,if not you could have a broken or blocked pipe.Very usual for it just to go though!