I have another problem with my 02' WRX. The car has 160K on the original engine , No mods of any kind. Regular great maintenace.
After a recent fill up I got a CEL blinking. The blinking mostly happens on light throttle and cruise. Full throttle and the light goes off. The engine is definatley missing. Idle is rough. Since it has been about 30k since the plugs had been changed I pulled all 4. Clyinder 1 and 2 are worn but a tan color . Cyl's 3 and 4 are dark to black as if running rich. Plug number 4 the worst.
I did get a code prior to the plugs being replaced P303. Now I test drive it and it does not generate a code and just blinks on occasion. I drove 3 times and shut the care off all time. Still no code. The engine is rough at Idle and a bit hesitant under hard acceleration. Pulls hard with the pedal mashed.
Any suggestion would be helpful.
Valves not checked.
All coil packs original.
MAS seems ok.