Certain codes will trigger limp home mode. Pull the code and reset via obd (have Mechanic do if you don't have obd reader yet). It will feel like a couple spark plugs wires are disconnected when in limp mode. Happened to me once right after a fuel fill up I thought I bought polluted

When my DISA valve died I had very similar experience. The difference being it ran ok at speed just idled like hell

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)