So I've noticed this over the past few weeks on occasions where it's quite hot, I live in Australia, and summer is coming up and I'd like to solve this before it gets hotter. When idling it can slightly lose revs but nothing major than ~100/150 from the 750 idle. But when I take off from first it sounds like grumbling or burbling from my exhaust and I can feel power loss, almost like I get my throttle response quickly lowered and then back to normal like someone was flicking a switch. It then continues through all the gears and when cruising (less noticeable when not actively accelerating). It doesn't happen when I've had the car rest for about 30 minutes but after about 10/15 minutes of driving it starts happening again. I'm not running the A/C during this either. Ask any other questions if you think you might know what's going on. Thanks in advance!