RPM fluctuation

[mountainman]

well, I have been working on my RPM fluctuation for a while and no change. It still does it at cruise speed ( anywhere between 1800 and 2200 rpm I get about a hundred rpf flux ). below or above everything is perfect. no other symptoms. I have cleaned the throttle body and changed the maf, oxygen sensors and aos. These were well overdue for a change anyway. I did a smoke test and found no vacuum leaks. I am wondering if the throttle position sensor or fuel injectors would give these symptoms. At 104K miles I am sure it could benefit from new injectors. Any thoughts? It is a 2004 boxster s with tiptronic. It does it in auto mode, or in any gear in manual mode and it does it with cruise control on as well..