'94 RPM's up & down

While driving my '94 Olds Sil. the RPM's will go up and down, and it appears to shift hard up and down in relation to the RPM's (I'm not too mechanically inclined, so please pardon my ignorance). The check engine light is not on, and has not been on in a while, but I do believe it came on about 2 months ago-just prior to the RPM problem starting.

My question is-is it likely the transmission or throttle positioning sensor or something else? I know typically most vehicles have certain components that are more likely to burn out before others...I just happen to know nothing about Oldsmobile "quirks".

Thanks for any ideas-I really appreciate it.

Christina