2000 Rodeo Idles Rough, Stalls, and CEL

Last night I filled up my truck and ever since then it was idling rough and when I stopped at the store it stalled on me. Its been fine since I got it until I filled up. The CEL light is on now and I hear a hissing noise from underneath the engine cover. Im thinking intake manifold gasket but I dont know??

By the way its a V6. Also when I bought it on xmas eve I checked the oil and it was fine. I checked it again because its been acting up and nothing was on the dip stick. I added a litre and its fine now. Isnt that a little harsh for oil consumption??

its got about 78k kms on it.

The good news is that if you hear a hiss you are correct it is probly from the manafold gasket, the bad news is since you're the secone owner the factory warrenty is now gone (unless you purchased an extended one). Since this happened after you filled up you may want to recheck to see if the gas cap is tight (common cause to toss a CEL). So tighten the cap and disconect the battery (or pull the ECU fuse for 15 mins or so). If you have a problem the CEL will come back on again. If there is an autozone in your area they will read the codes for free.

Oil useage. Yep Isuzu states that 1qt/1000miles is within spec. So the key is to keep an eye on your oil. The most common ways to decrease your oil consumption is to clean your EGR Valve and tube, EGR port (behind the intake butterfly), replace the PCV. Also, trying to keep the rings clean (add Chevron Techron concentrate every 3k, and once a year add a half can of sea foam to the oil (following the directions).

Seeing that your the second owner you probaley don't the maintance record so, doing all of these thing at once (I would do the additives for 2 tanks worth) should help the oil useage problems.

-Ryan