Hello and welcome to JustAnswer!
There are quite a few things that can turn the ETC light on. The throttle body, powertrain control module, wiring, MAP sensor, accelerator pedal position sensor, an intake restriction, vacuum leaks, etc can all turn the light on.
It sounds like you are having it go into limp-in where it is controlling RPM mainly by manipulation of spark and ignition. It will do this when the PCM thinks it's unable to control RPM using the throttle blade. This is usually due to a failure of the throttle body in one way or another.
What P codes are setting now?