Hello, newb to site and Supras. Just bought an 88 n/a auto with 134k on chassis and supposedly 60k ish on replacement 7m-ge(no supporting paperwork). I've searched threads and tried some stuff but only made limited progress. 1st-bypassed heater valve completely with 90* elbow-no change. 2nd-replaced 180* thermostat with 192*-no change. 3rd-raised front end and made a mess-no change. 4th-backward flushed heater core, lots of rusty water came out but no obstructing material-now have heat IF the motor is turning 2k or better but will cool back down when returned to idle. Question-could the water pump be weak? It doesn't leak and the bearings seem good as it doesn't wobble when grasped. Is this a common prob?