Honda element acceleration noises

I drive a 2006 Honda Element EX (not 4WD), which I bought new. It has a standard 5-speed transmission, and about 100K miles. In the past 24 months (25K miles), the clutch and transmission and have been replaced, as well as tires, brakes (twice) and a split axle cover. And it has been in the shop (out of town mechanics when i was traveling and the dealer where I bought it) for an as-yet unidentifiable noise that’s making me crazy. It has two other sporadic symptoms that may or may not be related. The main issue is a noise, a fluttering/clicking in the acceleration, which I hear most often at low speeds in low gears and which varies in volume for no apparent reason. It sounds a bit like when we used to use clothespins to put playing cards on our bicycle spokes. Possibly-related other issue #1: the accelerator sometimes sticks, and i have to “punch” it. This happens on start-up in first gear only. Possibly-related issue #2: twice in one day a few weeks ago, the accelerator suddenly accelerated without my prompting while I was in traffic.

The service folks at Honda have been kind and generous, arranging for a rental every time I’ve taken the car in for this, which has been at least half a dozen times. They can never hear the noise; they seem to rely on their computers to tell them of problems, but none appear. After the incident involving issue #2, I took it back in, reported both the extraneous issues. A different service rep suggested it may indicate a build-up of grease or dirt on some part (butterfly valve?), which would account for all three issues. When my regular service rep (a different person) called me to pick up the car, she said they’d not been able to hear the noise or repeat the problems. I asked whether they’d cleaned the part they’d mentioned, they said no, and agreed to keep it another hour or so. Later, when I picked it up, they said they’d done it but charged me nothing (I’d been told that cleaning the thing would be about $100). The noise was still there as I drove off the lot, although not as loud. Within a few days, the noise was as loud as ever.

I haven’t experienced the acceleration out of control since that one day, but i do still have to punch it from time to time on start up.

I really love this car, and want to keep it on the road for another 100K. Any ideas?