Suburu won't idol
2 Answers
there are any number of reasons...possibly twin timing belts...anyways the timing belt tensioner may be a bit loose causing fluctuations in idling~ as it goes slack, tight, slack, tight and with the reciprocating performance is unable to hold it steady~ just a theory, but I bet the tensioner is loose, tensioner bearing is worn and reciprocation because of the lack of tension is causing the problem~