Sup guys, I have a 2003 1500 5.7L with about 32000 miles on her. I've noticed that she tends to idle around 600-700 RPMs then will drop to around 400 RPMs, then she quickly revs herself back up to around normal (or so I hope ~700 RPM is normal). I've recently changed the plugs, wires, differential fluid, oil change, cleaned throttlebody and even tried Sea Foam. She still does it and it's drivin me crazy. She even does it when I come to a stop...I keep my fingers crossed that she doesn't stall out on me...
Also, I'm gettin roughly 9mpg in the city and i've never seen over ~13 on highway (only about a 2hr trip each way) wonderin if this has to do with the same prob.
Anybody have any ideas? Is this normal RPM range?

 

I also have a 1500 5.7l (03) and my rev's steady at around 550 (give or take). It does not fluctuate. Have you check your injectors or your fuel filter?

It could also be a vacumn line

 

Air filter? Good luck checking the fuel filter. My '03 with 95K gets around 14 in town and nearly 18 on the road at 80. You've covered all the bases except the air filter. A PCM reset may help -- are you using the O/H to determine the mileage?

 

Mike ...............is that on the overhead or hand calculated?
Al

 

Forgot to mention that I have an Intake, Cat-back exhaust, and Superchips (set to performance) and ya my intake filter shouldn't need to be cleaned yet, but I suppose I could pop 'er off and clean it.

 

an 03 5.7 with 32000 miles pshh that just broken in, mine has 82000, you could try to clean the sensors like the mass air flow with some electronics cleaner. It also might be bad gas, What kind do you use and how long has it sat since it doesn't seem like you drive it much.

 

^^^Hemi's don't have a mass air flow sensor..they're speed density.

Metal, mine 07 does the same exact thing word for word and has since new....it only has 5500 on the odo now and still does it. I plan on raiseing the idle whenever the predator handheld comes out...that should solve the prob.

 

I only put Shell Super in it for gas and the gas doesn't sit, I drive 'er everyday...I bought it used a year ago. Well it's nice to see im not the only person that has this "problem"...searched forums multiple times tryin to find info/another person with same scenario.