2011 GMC Terrain MAYBE stalling?

I have had my 2011 GMC Terrain for a couple of years now. It has never had great pickup time, but I always thought that was how the car was. A couple of times over the past year, I would be idle in a drive-thru & when I would try to accelerate, the car would not move at all. There was no revving of the engine, nothing. It was as if the car had completely shut off. The check engine light would then come on. The only way to fix it was to put the car in park, turn it off and restart the engine. Eventually, the check engine light would turn off after restarting the car. It only happened a handful of times & inconsistently, so I never got it checked out.

Last week, my car stalled the same way it would in the drive-thru, but at a red light on the road. It stalled and the check engine light came on once again. I had to turn my car off and on again and it drove fine. I finally took it to the shop & I had a manifold that was completely broken in half. The mechanic replaced the manifold, and I got my car back a few days ago. It has been driving much smoother and I thought the problem was solved for everything. Today, when leaving a parking lot, it stalled again. I was reversing out of a parking spot & the car would not move at all. I was pressing down on the gas and nothing was happening. This was the first time it happened when reversing.

I thought the problem would be solved by the manifold being replaced, but that didn't seem to fix it. I'm wondering if it's an electrical/connection issue with one of the sensors since it happens sporadically. I also know that GMCs are very oil-dependent cars, so could it do with that maybe? The mechanic mentioned nothing of anything else wrong when he scanned the vehicle. I'm hoping someone might be able to point me in the right direction on what to do/if this is a common occurrence with GMCs. I'm hoping to be getting a new car in a few months, so I don't want to put too much more money into repairing this one. Thank you in advance for any advice!