Since it happened all of a sudden (if I'm reading that correct) you might check the stat (toss it for a day/wont hurt anything). is it now running hot in stop & go or on the highway or both? I'd get a 3 row & there just was an informative thread on different alum rads having different tube sizes (see if you can retrieve it or scroll back several days/1 week). nothing else changed all of a sudden (timing/vac leak) that might be affecting this so k.i.s.s. a new rad sounds reasonable