we start it up it sucks the brake pedal to the floor?

Hello,

It sounds like you might have an issue with the brake booster.
The check valve on the booster can be faulty and causing the pedal to sink.

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor


First check all the hoses and connections to the booster.
Make sure the fluid is at correct level.
Remove the vacuum hose from the booster. You should have manifold vacuum at the check valve.
Operate engine a minimum of 10 seconds at fast idle. Stop engine, and let vehicle stand for 10 minutes. Then, apply brake pedal with approximately 89 N (20 lbs) of force. Brake pedal feel should be the same as that noted with engine operating. If brake pedal feels hard (no power assist), replace check valve and retest

I have attached diagrams for your reference.

Please let me know of any questions.

Thank you.