No codes but something is def wrong!

shishka

Episodes of strong hesitation (like rapid, tiny fuel cut-offs under acceleration or even just cruising) and bad idle, accompanied by backfiring under deceleration. Engine light flashed then stayed on today, but getting "N/A" codes. Also, when it happens, I get a burnt smell coming from the vents even with the air off.

When I say "episodes' I mean that it can go for days without seeing symptoms or I can have symptoms for days. It's random, which makes me think it's electrical, but then it tends to increase with engine temp so I have no idea.

Where should I look?? Recommend any tests before I give up and take it to the shop??