I have a ‘05 1500 with the 5.7L. Over the last few months, I have had an intermittent idle problem. When I restart a warm engine (not hot, not cold) and then drive a short distance, the engine idles very rough almost stalling. The engine idles very smooth while cold and after the initial stop. If I do not stop within a couple minutes, I do not experience the issue at all. The problem does not occur very often but the frequency has been increasing. Only one occurrence threw a code (P0300), but that has been cleared for a while now. I cleaned the throttle body and replaced the EGR valve, but no improvement. Any ideas?

 

It sounds like it could be your TPS.

 

Isnt the TPS built into the throttle body on the Hemi? Can that be tested?

It had another short spell over the weekend. P0300 is again coming up and the engine light is on.

 

p0300....engine misfire detected. Plugs, wires, coil ?

 

Yeah p0300 is a generic misfire and doesnt specify much. Could be coils, plugs, wires, loose connections, ECT.

 

it wouldn't be a bad idea to check your Idle Air Control valve. Mine was idling pretty rough a few years ago, pulled and cleaned with carb cleaner (not brake cleaner!) WD-40 and plopped back in - good to go. Didn't throw any codes though - which is kind of odd - just saying it wouldn't hurt I guess.

 

I finally solved the problem. After several weeks the problem continued to get worse. The problem still only was present at idle, 90 – 120 seconds into a warm start. I was suspecting the engine was running fine in open loop and fine in closed loop as long as the vehicle was fully up to operating temperature. My theory was the engine was calling for an AFR that was causing misfires. I also theorized the engine was getting false feedback during warm up but was ok after everything was up to operating temperature. I changed both of the upstream oxygen sensors and the problem is gone.
Oh by the way. The 2005 Hemi doesn’t have a TPS or IAC valve, but thanks for the input.