Took me a week longer than expected to return to the scene of the crime, but finally found a morning and went back determined to fix it. Took the front "bumper" off to reveal the engine in all its twin cylinder glory, located the coolant temp sensor, located under the thermostat housing, attached a scope and watched the voltage as the engine warmed up, nothing happened that pointed to the fault, until the man using the pnumatic drill across the street finally stopped and i could hear the exhaust blow, only very slightly, further investigation revealed that the flange on the exhaust that holds the o2 sensor had not been welded correctly, also knocking the rust off the flexible front section of the exhaust revealed more blowing. Sharp work with an exhaust bandage and gun gum changed the way the car ran completly. obviously the tiny bore of the exhaust and the way the twin cylinder engine runs was dragging excess o2 in and fooling the injection system, put back together and road tested (with a bag on my head) drives perfectly and happy customer, alls well that ends well.