i have a 97 ram 4x4 with a 5.9 and around 170,000 miles on it. horrible mileageat times, once in a while i can hear a vacuum leak and the motor will sometimes idle kinda rough when you hear it, also when it is colder out my truck will hardly idle and when it does it revs up and down about 500 rpm. this also happens once in a while when its warm out. i put a new fuel pump, spark plugs, wires, cap, rotor, and coil in this past winter. the truck will sometimes just die when you come up to a stop sign. i haven't had a check engine light come on since i gave it a tune up this past winter. just curious to see what people think my problem is and how i can fix it. my second question is i'm due for new exhaust soon. can i cut the cat and run true duals. i live in iowa so its not a big issue if i dont have a cat. i've heard of putting a sensor in each pipe will this work or not.

 

Sounds like the IAC. When I cold start mine sometimes the IAC will stick open and it idles like it has a cam in it for a few seconds, when the IAC is open it will sound like a vacuum leak.

 

Check your plenum gasket, there's a few right ups on here that tell you how to check it and replace it if that is shot. As for true dual exhaust with no cats will cause a few problems, there's an o2 sensor before and after the cat. The one after the cat is what will hurt you, it looks for how well the cat is performing and adjusts the computer accordingly. With it disconnected you will get a check engine light and the truck over time will run like crap, or you can reinstall it with out the cat and solve the cel but still have a truck that runs like crap lol