We have observed 3-m auroral E region plasma waves with a high-resolution 50-MHz radar interferometer at Ithaca. During postmidnight periods of very strong magnetic activity at Ottawa (L=3.5), the backscattered power and Doppler spectra vary rapidly with times and range and may have both mean Doppler shifts and half power widths in excess of 200 Hz (600 m/s). In addition, when the radar and magnetometer data imply tha the current is approximately parallel to the radar line of sight, sharp spectral peaks corresponding to phase velocities approaching 1 km/s sometimes appear suddenly. These persist for at most several tens of seconds at any particular range and their amplitude seems to be more strongly dependent on the drift velocity than is the strength of the wide spectral component, which generally broadens substantially before the high-velocity peak appears. The shape of the peaks and their time evolution lead us to believe that they represent a true two-stream instability, implying an ion acoustic velocity in the medium of about 900 m/s in extreme cases, which, in turn, means an E region electron temperature of as much as 2000 K or more at latitudes as low as L=3.5. This interpretation of the data is consistent with recent E region incoherent scatter measurements and helps to resolve some questions raised in connection with earlier coherent radar studies.