my wrx has recently started to play up
from cold start it seems to idle low and miss etc,when warm its fine.
it also seems to be using a fair bit of fuel,more tha normal.i have just had a downpipe fitted but the prob was there before....does this mean my afm is buggered???

 

Could be the coolant temp sensor that can play up when cold also have you tried cleaning your maf sensor? Oh an what condition are the plugs in? Try cleaning ir renewing them. Thats the things i would check 1st mate

 

Sounds like the coolant temp sensor to me, but could be Maf , Idle control valve or half a dozen other things. Best to do a diagnostic check.

 

is it possible to carry these out yourself???