99 Century Custom occasionally doesn't start.
 

Will crank once, pause a second or two then crank a few times before starting, occasionally not starting at all. Battery is fine, only code I get is a downstream oxygen sensory.

Explain the pause......like key turned off or the speed of the starter slows way down for a moment.....Also, will it start on alternative fuel? Missing spark?

The speed of the starter slows way down for a moment, then cranks a few more times to start. Like it has a very difficult time starting every time. More recently it takes a few times for it to start as it cranks once, then nothing. Sorry, don't know about starting on alternative fuel.

Sounds like it may have jumped time. How is the battery good? What actual test? What does it run like when it does start?

The battery is good and runs perfect after starting. Has 80k on the engine.

Sounds like a bad battery, connection, or battery cable to me.

How have you determined this?

Thank you for replying. The battery is in good condition. Another issue just started, sometimes after starting it will rev extremely high and nothing will bring it down. It will go 40mph without stepping on the gas. I have to turn it off and start it again.

You still didn't answer his question about how you verified the battery is fine.

It's important you give us numbers not 'it's good'. If a person cannot do that I move on.

OK, I'll get it tested again. Thanks again everyone.