I have a 03, 5.7 hemi with the hunting, surging, hesitation idle at under 1000rpm. Once above 1000rpm it runs fine, this is what the shop has done so far:
Clean TB

Replace throttle by wire

new battery (still had original factory one)

Ran great for a month or so then hesitation returned at low rpm. Since then I tried disconnecting the battery and touching the cables together to drain the main circuit board capacitors. The darn thing runs excellent for a week then same ol same ol again?? is it a vacuum leak or the main board?? never any codes on the dash.
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Does the car show any error codes?


Chances are it is a vacuum leak.

 

How many miles on the plugs? Has the PCV valve been cleaned/replaced?

 

No error codes ever, 43,000 miles on new plugs installed at 50,000 miles, current mileage 93,000 miles. why would this problem come and go at variable intervals? runs fine for a week or so then acts up momentarily. The mechanic need the truck to be running bad to trouble shoot it, I can't leave it with him for days on since I drive it daily for work. Would it be the main circuit board or should I just have the vacuum system smoke tested? Never thought about the PCV's.

 

I'd do the simple cheap stuff first as that fly by wire and battery won't have been cheap.
Set of plugs, new PCV new oil and filters and TB clean would've been my very first jobs before changing the other stuff.
Al.

 

Things done that lead up to parts replaced in my original post are:

TB cleaned, plugs checked, TB checked for correct readings when throttle by wire transmitted signal, battery was replaced last due to weak cell. Never once was a PCV mentioned. Oil always changed at 5000 miles with Mobil 1 synthetic.

 

Plugs are due every 30k.

 

By the book, yes. They're good to 40K, maybe more.

 

Vacuum leak, bad spark plug/plugs plugged PCV; all would be a mechanical issue weather it's a crack, open circuit or plugged valve. Why does it run good when I short the battery terminals together? does the computer compensate for any motor running faults??

No one else has had any issues like this??

 

I waited to post this just to verify the problem was corrected. After several trips back to the garage it was determined to replace the O2 sensors with factory Dodge parts. Mileage spiked up, performance improved, and not a single hesitation or chug the motor runs smooth and strong. Best part of all this the garage didn't charge me a thing, I think they were glad to see me not returning.