Tokyo stocks plunged Monday morning, with the Nikkei index briefly losing over 2 percent, weighed down by concern over European political turmoil and a sell-off of Toyota Motor as the impact of a vehicle test scandal lingers. The 225-issue Nikkei Stock Average dropped 708.15 points, or 1.82 percent, from Friday to 38,106.41. The broader Topix index was down 40.90 points, or 1.49 percent, at 2,705.71. The U.S. dollar was largely flat in the mid-157 yen range in Tokyo amid few fresh trading cues. At noon, the dollar fetched 157.44-45 yen compared with 157.40-50 yen in New York and 157.66-68 yen …