So ever since I got my car used (2016 Fiesta ST), I have not been able to rev past around 5,000 or so rpm. When I hit 5,000 rpm the throttle cuts out and rpm drop, like it's hitting redline or something. Also after this happens the turbo won't go more than 5 pounds of boost and it acts oddly by whistling when I accelerate. I have to turn the car off for a minute and than everything is back to normal (until I do it again on accident). So I got the COBB accessport and my redline is set at 6500 rpm but this problem still occurs. The car drives normally until I floor it and it cuts off at 5k rpm (which happens easily since it spools up so fast before I realize). This is very strage and I can't seem to find anyone with the same problem. Please help, so I potentially don't blow my engine.