My 2000 Discovery II starts fine but the RPMs immediately drop very low where it stays running rough for about 20 seconds then dies. I turned it off and it starts right back up but does the same thing. Is this something that a bad CPS would cause?

 

Definitely not CPS if it fires and runs at all. Sounds more like MAF sensor, vac leak between the MAF and the manifold, or fuel pump. Others may have more specific suggestions.

 

I dunno, CPS is worth a look. I just had to change mine and I was experiencing similar symptoms. The CPS can do weird things before it goes completely dead and cause a no start. My would truck was dying while I was driving it and in the end wouldn't start when hot. Changed the CPS ( hope you have small hands) and I have not had any problems, just did this yesterday.

 

Oh yeah, check your codes! I wasn't getting any when the CPS was going bad. Yours might turn up something else and point you in a different direction. Just saying the CPS could be a starting point. They are only $70 bucks and knowing you have a new one can't hurt piece of mind.

 

Likely on the mark, here. And I second the notion of the need for a scanner. The only thing I would add is that I know (from my ScanGauge) that 20 seconds is about how long my truck takes at start-up to go from open loop to closed loop.

 

Each time I try to start it, it runs for a shorter amount of time until now it just turns over and doesn't start.

 

What are your codes? This would be step #1 on pinpointing the issue.

 

CPS, dude.