Ford Focus 2003

My Ford has 59,000 miles. When I start the car sometimes (not consistent) it seems to be having a hard time getting the gas, like if it has a choke its not working, in both park and drive. Then the brake vacuum fails and I have no brakes, pedal goes to floor. I’ve had it to two different mechanics and they’ve talked to Ford and they don’t know what the problem is. The things they tried:changed pcv hose, brake booster hose,repair hood cowl seal for water running down PFE sensor ECR control selenoid.SP? I sit there give it gas and I can usually get it fix itself. Can you PLEASE HELP.