when i start my truck or put into drive it idles very high and fluctuates sometimes it reves itself to 2k and stays there .. i know it has to be a sensor on the throttle body but i dont want to buy the tps ,iac and the map....i cleaned my IAC last year ... should i try the tps first ?

 

Test the TPS first. Use a meter, see what output voltage (center wire I think) is at idle, should be right around 1 volt.