Engine Performance problem
2001 Mazda 323 4 cyl Front Wheel Drive Manual 150000 miles
My mazda has been running great but recently shuddered to a stop. The garage cleaned the catalytic convertor and it went fine for 2 weeks. Now its not starting. It turns over but but needs push/tow to start her. Once going, she judders for a while then runs smooth. Garage cant find problem. Engine maintenance light is flashing. Computer showed no problem. Help anyone.