Nissan Repair: cold start, air control valve, filter belts

Question
ok, I have replaced the coolant temp. sensor and tuned up my 98 nissan maxima w/plugs,air filter,fuel filter,belts. I am having to hold the gas pedal down partway to get the car to start. After strating and it sits 4 0r 5 hours it will start right back up with no problem. If it sits more than 8 hours we have to use the gas pedal to start it. Car runs great. What next?

Answer
Debra,

Check the cold start circuit.  The temperature sensor you had replaced has to be the one that sends information to the computer and not the one that provides information for the gauge.  If the sensor does not set a cold start condition it will not fatten up the fuel miuxture or increase idle.  Also, the idle air control valve could be stuck and that would cause the non start bad idle condition at cold start.  For me I would be looking at the idle air control valve first and clean or replace it and make sure the throttle body is clean as well as the passage for the idle air control valve.