Brake Master Cylinder problems of the 2014 Kia Motor Soul

Intermittent loss of brakes (no pressure, straight to the floor, pumping does not help), extremely difficult to replicate on command. After loss of brakes in a parking lot, then at an intersection, replaced all rotors/pads, master cylinder and no leaks or other warning signs. Given issue with replication, never received a diagnostic code after 4 weeks of trying. Replaced abs system, as only option left to fix a braking issue, and issue appears to be resolved. Kia has had problems with abs modules but only recalled for certain vehicles with fire hazard. Spent thousands of dollars trying to resolve this issue and could not drive due to safety hazard for over 1 month while trying to figure out the problem.

Shortly after buying my new 2014 kia Soul in March 2014, I noticed that acceleration delayed usually from a stop light, stop sign or stop/go traffic and would need to pump gas for car to move then it will take off quick and almost become out of control, also feels as though lose power steering and proper braking. Dealer service could not find any error codes on scan so no fix. After 2nd attempt to look at problem I was told by service manager that if I was driving in eco mode that could be the issue. If kia knows this why even offer that mode? I also have a problem with the passenger front seat belt that only allows slight movement before it locks tight and does not retract without unlatching completely. Upon inspecting other cars on lot with service manager we found the optima, Soul, sportage all do the same thing on passenger front only allowing extending the seatbelt/or movement about halfway forward before it locks and will not retract. The gas mileage listed on window tag was over-inflated at 27 mpg it seems to average closer to 23-24 mpg. Finally I was in an accident which I rear-ended someone at stoplight and while I felt there should have been plenty of time to stop the brakes did not feel as though they worked at all, the car just kept going, the weather was dry. It was suggested by a brake & tire specialist to go to dealer for full inspection, but I hesitate to return to kia do to all my other issues that can¿¿t be figured out because the diagnostics can never find an error code. I will be taking my car in for a complete tear down by a 3rd party brake specialist for brake/sensor/master cylinder inspection as I don't even feel safe to drive this new car with approx 17,000 miles. I have since opened a case with kia consumer assistance due to the many ongoing issues.