My 2001 XG300's rpms get erratic when car is stopped. When I take off from a red light it struggles past 20 mph and the check engine light will come on until I let go of the gas, then it usually goes back to normal. While driving the rpms aren't anywhere near steady. Assuming it's the Throttle Body? Could use some assistance

It sounds like you may be having a problem with the throttle position sensor in the engine compartment.
It's expensive, but you should try some fuel injector cleaner before you do any major work.
If you see improvement with the cleaner, consider having the injectors cleaned. It may be all you need and it is cheaper than having the sensor changed.
Best wishes!