ok - I did do a search on this but nothing seems to answer my questions. I thru 4 cel codes today. P0171 (A/F RUNNING LEAN) P0302 (MISFIRE CYL 2)
P0304 (MISFIRE CYL 4) - plus ????? that the access port could not read. Cobb techs were no help. I am running stage 2 93 octane - its been about 6 months w/ the the acces port with out any problems - I am running gt spec header, perrin down pipe (catless), perrin cel delete, HKS carbon TI, using that stuff about 8 months w/ no problems. I am also still running the stock intake - I don't know if this makes a difference but in about the last 2 weeks my gas milage has dropped 30 or 40 miles to a full tank - my gas milage really sucks now - the car (06 WRX TR) is also idling kinda funny - idle drops 2 about 400 500 rpms - starts to stall than catches itself & jumps back up 2 about 1000 rpms & starts again to do the same thing - the ruff idle started this morning but did not show the codes until I was on my way home. the car has about 10,200 miles on it - it gets regular oil changes @ 2500 miles royal purple w/ subie factory filters - noone seems to have any ideas around so please help me - thanks

 

What did Cobb say about the fact you're running their off the shelf stage 2 map with an aftermarket header?

 

I am getting the same thing with my CEL. it comes on a various times and shows no code, just ??????

 

The five question mark code seems to always go along with a misfire. Usually the ????? will not show up by itself, but with a misfire code or several misfire codes.
Might want to use a OBD2 scanner next time you get the code rather than the AP to read it. AP can't read every code.

 

IIRC, the ????? means that its a subaru code that the dealer can use their special scanner to find out what the problem for the misfire is. that ????? will probably let the dealer know that if the misfire is because of a bad coilpack or a bad spark plug.