vwglenn wrote:About a minute later I started burping and it did so about three or four times.
Are you sure its burps and not a mixture problem? I don't think I've ever experienced burps although I do regularly experience a "miss" if I advance the throttle rapidly during the takeoff roll--I don't know if this is what others call a burp or not. I blame my "miss" on the lack of an accelerator pump. Anecdotally, this seems to happen less the richer I have the needle adjusted.
I have also experienced surging near idle settings when in a descent (my working theory is at a fixed throttle setting, the propeller spins faster in a descent than on the ground so the same amount of fuel is metered into a larger amount of air causing the mixture to become leaner. If the setting is pretty marginal on the ground, it might become impossible to adjust the mixture rich enough while in the descent and it surges).
I also regularly pull the mixture lean during climb-out for additional power, but if I level out and leave the throttle at WOT, I need to richen the mixture to keep it running smoothly. This seemed counter-intuitive at first, since I expect to lean at altitude, but I also never fly other airplanes at WOT in cruise :-)
None of these sound quite like what you describe, but have you overruled a mixture problem at 2900 rpm? Intuitively, I would expect you to be moving fuel (and air) through the cowl fast enough at that power setting not to have to worry much about vapor issues. I also admit that the Jabiru 3300 is probably completely different than the Aerovee I fly.