My subaru had a problem with power when i accelerate so i changed sparks plugs but still it has no power
Try swapping out the MAF sensor, as it controls acceleration; an intermittent one with "bog" and prohibit smooth acceleration. Do you have a CEL? A PO301-4 would mean a wet, insufficiently pushed on, corroded, or shorting to ground ignition wire. Proceed and ask again as necessary.
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