Engine idles rough and backfires
Any codes? Do you have a scan tool?
It sounds like a timing problem, possibly a bad crankshaft position sensor.
The timing chain might have shifted a cog, or stretched and there’s too much play between the crankshaft and the camshaft. Suggest to first however verify the routine maintenance is up to date, spark plugs are ok, all diagnostic codes have been read out, etc. It may just be misfiring for example, due to a bad spark plug, coil pack, etc. In any event , to protect your $$$$, this is something that requires fixing w/due speed b/c it could be damaging the catalytic converter.