MurrayZA

Hi there, I have an 01 WRX PPP, was accelerating hard in 4th when the car retarded heavily and dumped enough badly burnt / unburnt fuel into the exhaust to cause a smoke puff visible in the rear view. This was just after I had filled up my tank. Could I have got a bad batch of fuel ? Anyone had this before ? Any ideas if there is damage ? Car still seems to be running fine, though with a little flat spot (only in 4th/5th) around the rpm it retarded in
(learned knock correction) ? No safe mode or limp mode was entered
by the ECU and no CEL was displayed. Conditions are relatively hot (30 odd degrees C / 86 Farenheit).