Issue appears after driving more than 10 minutes at highway speeds when you get to the next stoplight RPMs drop below normal idle, and car will either stall or begin to stall if you don't put it into neutral before coming to a complete stop. The issue only appears when the wheels have stopped turning, and the car is in gear. I've only had it stall once I had been driving 70MPH on the highway, and it failed at the next stop light. Started right back up no problem after that. RPMs always drop at red lights or when the vehicle is stopped, but rarely to the point of stalling. Unfortunately I didn't collect any data from this event however I will update when that happens. Changing sparks, and coil packs later as well at intake manifold gasket.