I just hooked up my profec b using the instructions on mkiv on how to hook up the blitz unit. Worked fine in low boost but when i tried it in high as i shifted in to 4th the car stalled. I pulled over and started the car and the boost guage and tach needles were floating but boost was in floating in vacuum the car was stuttering and jerking but moving. What could this be? Any help will be greatly appreciated.