Have same problem with 1993 Impreza in cold weather...replaced ECT sensor, reset ECU, then replaced O2 sensors, MAP, new tune-up, new injectors...still problems. My mechanic is mostly bald due to the hair he's pulled out trying to fix this! Now, he says someone told the 1993 has Pre-injectors for cold weather starting! Anyone ever heard of this...and what can be done to fix this?