Mine was the exact same way i would idle till it warmed up and the fans would cycle start driving it bam exactly what your talking about. I was searching for months and posting sooo many threads about this problem because it would drive me crazy I replaced my rad, 3 oem thermostats, rad caps, running lines differently etc. Blowing out the stop leak crap from my heatercore fixed it. IMO I wouldn't put another dose of subaru conditioner this round.