Since getting HPtuners and modifying my tune, I have not been able to exceed 3800 RPM without my engine shutting down abruptly. The throttle seems to close and I can hear a suction or pressure build in my snorkel. Aluminum 5.3 bored, stock cam in a Land Rover Disco 2. If I can get up to speed I would yell hooray. The scan shows a max of 22.04 lb/min of mass airflow.