Got a bit of a strange prob with me saph at the mo

The car has recently had an MSD Chip, greens and 3bar fitted and has been setup properly. The car runs sweet most of the time, but it has developed a strange intermittent problem. It has happened twice now in a week and both times in 4th gear. Basically I'm gunning down the road in 4th and I get a bit of a pop noise and I loose all power. The car will not rev. Take it out of gear and plant me foot on the throttle and nothing happens The revs just go down. I need to let the car drop to idle for a couple of seconds and then everything is alright

Any suggestions on what could cause this??

M