Engine Water Noise and shifting RPM

[pipes1]

Hello all, ive got an 01 MGM LS with about 210,000 km's on it, and the engine light appeared for the first time in my 2 year ownership of the car. i scanned it and it read out a small evap. leak code, which was a sigh of relief. My problem is that im starting to hear a gushing noise, like water running through a hose (or intake...). I do have the plastic intake on there at the moment although i have done a quick visual inspection and haven't found any visible leaking and all of my temperature and fluid levels seem OK, so my question is could the noise be related to the evap leak, or is it part of a bigger problem coming...?... i also could just be noticing the noise now when its been there all along.

My shifting RPM problem occurs when i shift from park into either drive or reverse when the car is cold, the rpm's drop substantially and one time the engine even stalled out, i do give it about 5 mins to warm up and it still does this, and when i am stopped in traffic or at a drive-through, the rpms go pretty low and start to go up and down, and when i shift back into park they go back up to normal (this happens ONLY when its cold outside (0<)) . there is also a possibility of tranny problems as it shifts pretty hard into 2nd.

If anyone has any insight or advice as to what to look into, that would be greatly appreciated....

[sly]

the small evap leak is usually a hose cracked/loose on the evap box under the trunk or the gas cap seal is dirty. Try cleaning the seal first and putting the gas cap back on. Should go away in a few miles. The water gushing sound you hear inside the car is typically coolant rushing into the heater core on acceleration. If you usually have the AC going or stereo bumping... you probably don't hear it. That sound is normal if the coolant system has been drained and not burped completely leaving an air pocket on the heater hose. It's nothing to worry about as long as there's no major leaks. Watch the level in the coolant fill tank and make sure it's not dropping. That would indicate a leak somewhere.

[86VickyLX]

If you hear a water rushing noise from inside the car, you probably have air in the cooling system. It's common on aeros and whales.

[pipes1]

Thanks for the info guys, the box under the trunk lid I'll have to look into as I just baught new tires and got pretty creative when I stuffed them in my trunk. Is the Evap box near the fuel cut of or directly under the lid? And anyone got any advice on the rpm problem? Thanks for the help.

[tjc78]

The Evap box is under the car in the middle of the trunk pan.

[IPreferDIY]

One wild guess for the RPM issue would be the PCV valve if it's original, though I guess it could be a IAC issue too. When I changed my presumably original PCV valve recently, the only thing it affected was how the engine/computer went about finding its idle after a cold start. Maybe a really bad one would have more obvious effects? Then again, you say it's only a problem when you put it in gear, so IDK. I don't have any personal experience with the IAC, but it comes up a lot for idle problems. Another thing I'd throw into the mix is EGR valve, but I doubt it. I'm far from being an expert, so I'm just throwing out things to think about. I guess the evap issue wouldn't have any effect on fuel pressure. Pressure would seem to be a pump issue, so presumably fume collection wouldn't affect that.