yes it is on the throttle boby. you can acutally test to see if its working by unplugging it. this will put the ecu into limp mode and it will run off of the ecu preprogrammed values instead of the sensors. this also sets the CEL. so if you unplug it and the problem goes away you know that is the culprit. if it doesnt stop the symptom reset the ecu by unplugging the battery for about 15minutes to get rid of the CEL and move on to your next diagnosis. if it is a vaccum line you can spray the vaccum lines with carb cleaner while theengine is running and if the rpms increase the area that you just sprayed is the leak.

does the car idle correctly or is it just doing it under load???? if it idles wrong or jumpy then it most likely is a vaccum leak