Hello everyone,
I have had this equinox since 2012 and it has gone through some major repairs in its life - luckily it was all warranty work. I am currently at 165,000 km.

Here is what has been done in the past:
Water pump and timing chain and tensioners replaced at 100k km right before warranty expired.
Spark plugs, T-stat, rear diff fluid, and transfer case fluid replaced at 100k km as well.
Transmission fluid changed at around 115k km.
Both VVT solenoids failed (separate times) and were replaced.
Excessive oil consumption warranty performed which replaced the main timing chain, tensioners, piston rings, etc. at around 120,000 km.

For the last couple of years, I have noticed a weird intermittent vibration/rattle from the engine bay on cold starts.. but it had a rhythm to it (rattle for a second, then quiet, rattle for a second, then quiet) and it would get louder as soon as I put it in reverse to back out of my driveway. However, it is very intermittent.. sometimes I don't hear it at all for weeks and then it comes back for weeks. I tried to get a video of it and I'll try to upload it. Once I've driven for about 5-10 seconds, the noise is gone.

Just recently, I noticed a leak in the transmission cooler line, so I replaced that myself and then had a shop do a transmission fluid change.
I also was noticing some hesitation in the transmission (before the cooler line was replaced) so I ordered new VVT solenoids and replaced them about 2 months ago.

I feel as though the new VVT solenoids made the transmission run better but now it is definitely getting worse. During hard braking, the transmission will hang a bit before downshifting.. it doesn't jar the vehicle or anything but I can just notice it more often now and even during light braking. During acceleration, I can sometimes feel it as well. It seems to be very intermittent and it also seems to be worse after the vehicle has warmed up.
When I leave my parkade at work everyday, there are some steep inclines (40-50% grades) and it will upshift midway through the first ramp which usually is a pretty rough shift and jars the vehicle a bit..

Thoughts on what could be causing this?
Are there diagnostics the dealership could run to figure it out? I've taken vehicles to dealerships with intermittent issues before and every single time, I leave without a solution or that they couldn't replicate the issue..

Edit: Added the video to my google drive for the rattle. Thinking more about this.. does it sound like intermittent chain slap? Rattle Video