Limp mode PLS HELP

[Bgarza1122]

Was driving on the freeway when my car went into a sort of limp mode and eventually fell into neutral when I got off the freeway. I shut the car off and back on, and it drove fine for a bit before the same issue occurred as I was able to pull into an Oreilys. There is a grinding noise which seems to be coming from the valve area but after inspection, valves and rocket arms are not bent. I have a code for O2 sensor (1221) and oreillys tested my alternator to be bad. Car starts fine for a minute or two before grinding sound starts. Planning on changing O2 sensor and alternator, but what can the grinding be??? I’ve read it possibly being the valve spacing. PLEASE HELP

88 325i auto

[ADEN]

Many issues can cause grinding, Valve gap will cause ticking or knocking noise, Try to provide more info maybe a video.

[It's Soda Not Pop]

Are you sure it wasn't misfiring and that's what the grinding noise was. Because if your alternator is dying it could be that you're not getting enough spark to ignite the fuel properly.

[Bgarza1122]

I believe the grinding noise to be the starter grinding with the flywheel.