420A RPMs all over the place and rough idle

[95eclispe]

So for a while now my car has been idling all over the place. One minute its idling at 1000 RPMs then it increases on its own to 2000 RPMs without me hitting the gas and stays there for a while before dropping back down to 1000 RPMs. Other times it drops below 600 RPMs as if it wants to turn off which sometimes it does. If it doesn't turn off it increases RPMs on its own but when it does turn off from running it wont turn back on until the car cools down.

I'm not sure if they are completely different topics if it runs hot it wont turn on until the car is cold again so i cant run into the store unless it stays running.

Any ideas what the issues might be or if anyone has had some similar issues?

 

[genegoesfast]

Coolant temp sensor? I've also seen a bad tps make the car idle like crap. Could also be a bad isc motor. Are you throwing any codes?

 

[95eclispe]

Coolant temp sensor? I've also seen a bad tps make the car idle like crap. Could also be a bad isc motor. Are you throwing any codes?

Yea, only codes that come up is EGR valve and O2 sensor, but I changed out both O2 sensors. And my car doesn't have an EGR valve.

The CEL comes on and off but when its on the car runs normal. When it goes off it runs like its in limp mode

 

[genegoesfast]

The egr valve is properly blocked off right? If its leaking, that could be the issue.

 

[95eclispe]

honestly im not sure. how would i check? when i took it to my mechanic to replace the egr valve he said my car doesnt have one it was taken out by the previous owner.

 

[dsmspickdad]

420A correct? sounds like ISC motor, vacuum leak at the throttle body usually I found the tube recirculates the PVC leaks. Hope this helps usually doesn't throw a CEL.

 

[johnmel]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)
This might help you out.