I have a bone stock 04 evo. The car has a slight stumble only at idle, it is small but I can definitely hear and feel it. So far I have cleaned the maf, has a new filter, new spark plugs, and new coils. I have not been able to find any loose vacuum hoses. I have not done a boost leak test yet. I am throwing te code p300 I know it's a common one but I know it's actually missing at idle and it's not from something else.

Does anyone have any other suggestions?

 

I say do a boost leak test as well when you get a chance.

Also, has the Ecu been touched before?

Dont rule out the IAC, but i highly doubt thats it... just throwing out there.

 

N e 1 else?