Recently my girldfriend's rodeo has started having an issue with not wanting to start. When you try to start it everything electrical comes on in the car when the key is turned to "acc", but when you try and actually start it everything goes out like you just disconnected the battery. No click, no turnover, and everything electrical off. Turn the key back off the start position and all electrical comes back on.

It will do this anywhere from once to several times then start ok. Yesterday it was doing this and would not start at all finally. I popped the hood then tried and it started up. I then unhooked the battery made sure terminals were clean (neg had very little corrosion on it) and tightened everything back down. Battery is only 3 months old and was testing good voltage wise.

After checking/tightning terminals the car would start sometimes and soemtimes it would do the above. The only thing I have done recently was change the O2 sensors before the cat. converter on each side. It has 40,000 miles on it.

Am I looking at a connection, battery, alternator, or something completely differenet here?

Thank for you time.

Mine has done that twice. First time was the starter went bad (big pain to change on 4x4 rodeos) and the second time was a loose negative cable on the battery.

...starter went bad (big pain to change on 4x4 rodeos)...

Wonderful, she has the 4x4 model. Thanks for the heads up.