98 Camaro Engine RPM

I have a 98 Camaro V6 3800, the engine rpm's seem to go up and down while at highway speeds. The throttle is kept in the same position but yet the vehicle acts as though I am pulseing the gas pedal? Any idea what might cause this to happen? Any help would be appreciated.

does it feel like your loosing speed or u may be in the wrong gear? if so then your tranny is going out....my car did that for a few weeks, then i was driving along and it droped while i was on the highway, then shot all the way up and the tranny went......

My Camaro is an automatic, and it doesn't seem to lose any power. Does anyone know if a failing throttle postion sensor would have that effect?