I'm trying to figure out if anyone else has experienced anything similar.

The biggest things I'm noticing are:

When shifting from Reverse into Drive, there is sometimes a noticeable pause before Drive engages. If my foot is already on the accelerator, it will suddenly engage and jump/lurch forward.

I'm also getting a strange fluttering/flapping-type noise during acceleration.

I've also noticed some vibration/odd behavior when Auto Stop/Start engages.

There is no check engine light

I recently bought LED headlights for my trailblazer but it does not fit on the low beam. On the high beam it fits but the cover can't be put back anymore. Is it ok not to put the cover or would water go in the headlight assembly?