Car: 2009 Mini Cooper base model with manual transmission 90,000 miles. Owned since late April 2021

Did a few searches but didn't find a thread about my issue. I either suck at searching or there isn't a thread yet, or both.

Anyway, I recently replaced the head-cover gasket, VANOS solenoid, and both cam position censors, on my R56(manual trans). Everything seemed fine for the first 4-5 miles but as I was accelerating to highway speed on a slight up-slope, the car began shaking. Looked around on the web to see if my maintenance had a history of causing this and found some info that ignition coil packs might be arcing, causing the engine to surge. One coil pack had some of the rubber insulation missing so I replaced it. This didn't resolve the issue. The next time it happened I noticed that there was no change in the revs. The engine hasn't thrown any codes (misfire or otherwise). This makes me think it's more an external issue (like motor mounts), than an internal one. The brake light indicator is on (red). I've inspected the brakes and there doesn't seem to be any problem. I replaced the front rotors and pads several weeks ago. The wear censor wire had been cut by a previous owner, so I replaced it when I performed the replacement. Still intend to do the rear brakes, but didn't see any obvious issues. Small wear lip on the rotors and newish pads.

Here is the full list of symptoms:
1. Car sometimes shakes when accelerating
2. Happens when revs are below 2,500
3. Most common when going from 1st-2nd
4. More likely to occur when on a road with an upward slope
5. Does not happen at high speeds
6. Engine runs like a top (no rough idle or rev surging)
7. No associated noises (clunking, etc.)
8. As revs increase, the shaking goes away
9. No engine codes
10. Red "BRAKE" light

My initial thought is that it's either bad motor/transmission mounts.

Any help would be much appreciated.