For anyone interested..., the problem was solved when the water pump went out and the tech discovered the timing had shifted. During dis-assemble, he observed alignment marks were not lined up where they were supposed to be - they were off approximately two sprokets. When all the new parts were installed and lined up per Saturn specs, the car now runs like it should have all along. Hard to tell how this happened in the first place but now, the engine runs great. Mystery solved.