I've got a similar problem to surging and stalling below...minus the stalling. My '03 Element is older, with about 140k miles, but it's past mechanical issues include replacing the ac clutch mechanism and, about a year back, the catalytic converter with a refurbished one. That said, after sitting idly for a couple weeks, I turned the engine over on the eve of my commute from New Orleans to Pittsburgh. What I noticed was a high idle, around 2k, which would settle into the normal <1k rpm range after a tap on the accelerator. What then happens is a surge with periodicity, every second or so, from 1k to 2k rpms. The vehicle will drive normally enough when applying the accelerator, however, the moment I let up on it, the periodic surge resumes, even at highway speeds. Needless to say I opted not to take the 1200 mile drive! Diagnostic ideas are welcome...