When I start my car, I let it warm up and the rpm drops after a few minutes. Now when I drive it and lets say I come to a stop, my idle fluctuate just like the video but its very very tiny. Like the rpm needle moves a little then backs down. I hear the engine too.

 

I have the JWT popcharger and just installed the spacer as well. Initially I actually pinched the rubber shroud surrounding the oil cap and it resulted in a terrible idle and sound. Fixed that once I disassembled and reassembled. You may have a vacuum leak, but seems more like it's the clearance between the strut bar. I added 3 washers to each of the inner most bolts on each side's mounting point and gave the bar a couple spins out to get the clearance right. I didn't even do an ECU reset. Seems to have learned it fine. Idle is smooth and the gain is definitely noticeable along with the new growl from the engine.

Just double and triple check your work...make sure the thicker side of the spacer is towards the front of the car, gasket is placed right...blah blah blah. Let us know if you fix your issue