HELP Maxima just quit!!!!

My maxima just quit running the other day. I do not get a Check Engine light. The car starts but only idles at 400rpm when I hit the gas it only goes to 500rpm. I have changed the fuel filter. The fuel pump is good. My distributor cap was cracked so I replaced it. It has kind of new wires and spark plugs. The timing belt was changed at 99750 and my car is now at 132000. It sounds like a timing problem to me but can anyone please help me. Someone said it sounded like a sensor but I can not run the ECU because it states the car has to be at 2000rpm. Sensors are to expensive to just change randomly how can I test these or what do you think is wrong with my car?