I'm the third owner of an '83 Impreza L wagon with 170,000 miles on the odometer. Second owner said she thought engine had been replaced at around 150,000. Anyway, the engine has developed a problem and I need some help, Please! The engine seems to be missing at rpms below about 3000 when it's cold and misfiring at the same when engine warms up. Once I get past 3200 rpm the power kicks back in. I replaced the spark plugs (goodness knows they needed it) and, get this--that seemed to correct the problem for a few days. When it started missing again, I checked the spark plugs and they looked fine. When the engine warms up there is a popping sound coming from behind the engine. Does this mean it is firing late? Any suggestions for this 51-year-old granny? Thanks!