I ran the battery down and ever since it idles around 300 or 400 rpm it's always idled low around 600 rpm but now its too low. Any ideas where to look? I put a new battery in it. It is a 2003 Yukon with the 5.3 V8.

 

I would start by going to AZ and see if there are any engine code.

 

Low voltage can cause some weird drivability issues. The tps may need to be reset or replaced? I think you will need to have it scanned with a scanner that does more than generic obdII.

 

One thing to try is doing a hard reset on ECM, (used to lots of them on cadillacs after dead batteries to solve driveability complaints) what you do is disconnect both cables from battery and jumper them together, leave it that way for at least 30 seconds to a couple of minutes and then reconnect everything, sometimes that will work, otherwise get the codes checked and let us know what it has.

 

Thanks guys for the replys I'll try the hard reset. And have it scanned.

 

Could you tell me what the TPS is? How do you reset it?

 

TPS= Throttle Position Sensor. i've worked on a lot of GMs and never had to replace one.

 

make sure the key is on when you touch the battery cables together.