Subaru engine cleaner on an Inline four.

Yeah from memeory i think its about 19 bucks a can

I used some Sea-Foam on my DC2R, idle was steadier. It also made the car feel a bit smoother, and the TB and intake manifold wear totally clear of carbon, oil and discoloration. worked perfectly. Someone should take their plugs out before they do it and after to see if the combustion chamber is visibly cleaner??