Problem with front Oxygen sensor?

[echang]

I own a 94 3kgt SL that's pretty much garaged most of the time, but since the end of last year I had a problem, when I leave the engine idle it sometimes just stalls, the other times it's either having high idle speed (2k rpm) or the RPM bounce between 1.5k and 2.5k when idling. Having just purchased my new house I am in a pretty tight situation right now, but I decided to bring the car to the dealer and have it checked out.

After 3 days, 200 USD$ they told me they couldn't get a reading from ECU, and they need to replace the ECU (costs 2,200 dollars) and then try to find out what the problem is. I figure it's probably gonna cost me both arms and legs, I decided to hold. I am no mechanic, but I thought... if the ECU is totally messed up the problem is probably not just idle speed. So I got a data logger for palmpilot and hooked it up to the ECU terminal. And BOOM! Everything works flawlessly, I got all the data reading from the ECU (it's Cannon Mitsubishi in Lakeland, FL)

I could only find one problem on the ECU data, the front Oxygen sensor voltage reads zero all the time, while the rear senser isn't. Could it be a dead sensor? and if it is... could it be the problem that's causing stall while idle? I am also suspecting hose leak hence the ECU could not negotiate a stable idle speed?