I have a 98 328i with 38k miles (just out of warranty). The idle will SOMETIMES flucuate between 300-700 rpm, and it seems to do it when ever it wants to (hot or cold, sometimes after 30 minutes of driving). I find that some of the time, stomping on the gas and taking it to around 5000+ rmp will resolve the problem when it comes back to idle. I have just had the Idle control valve replaced and all the intake components lubed. The problem is still there. It seems to be something mechanical (not computer related) but I could be wrong...this is just a hunch. Anyone know what might be going on here? what can be done to rectify this. Its more anoying then anything else. Please help.