Hey guys can you please help with my problem.

• I have a 97 LS400 that upon starting idles extremely rough with fluctuating RPM.
• It occasionally dies after 5 seconds of idling.
• It doesn't do this when the engine is warm
• At about the same time as this started I also noticed that the engine overheats at stop lights. (Not sure these two are related.)

I really appreciate any help!
Thanks!!

 

I could really use some help here.
I should also probably mention that the car has 250,000 miles. The rough idle is more of a surging RPM at first and then (if it doesn't stall) it turns to a really rough idle before settling down.

It seems like an air problem, but I don't know where to start really.
Thanks

 

Idle air control valve, ECU, Air flow meter, Egr but egr would keep it running bad. At cold start up it runs with a basic no input from the sensors condition, after warm up time and the O2 sensors heat up then it goes closed loop and then it starts using the sensors to operate, I'm not sure if a bad O2 heater could cause that or not and delay closed loop. Its really just guess work without using a good scan tool to see what is happening.

 

Thanks dicer!
My son tells me it is intermittent if that makes any difference.