SW2 won't start
 

My 1999 1.9 SW2 started running rough then quit running completly. It would try to restart ( run on maybe two cylinders then quit). Had it towed home and checked the computer for codes. The only code indicated was low voltage on the upstream O2 sensor. Would this cause the engine to not run at all?

Did any dash lights come on when it started acting up? These cars are extremely voltage sensitive. The symptoms point to a low voltage condition which is usually accompanied by the usual dash trouble lights.

No dash warning lights came on. After sitting over night it will crank and run at fast idle untill the throttle is opened, then it dies.

Has the ECTS ever been replaced? Try pushing and holding the gas pedal to the floor while cranking the engine. A bad ECTS will sometimes result in a flooded condition which is more noticeable when the engine is warm.

Sounds like the ETCS and connector.