ok i have had this idle problem with my car forever.
There car idles with the a/c off but when u turn it on the car surges and tries to die. The car also tries to slip out of 4th gear when your crusing with the a/c on. I was reading in the Haynes repair manual and i came across an Air conditioning clutch control. It is suppose to delay clutch engagement to allow the IAC valve to adjust the idle speed of the engine. Could this be what is worn with my car. I have already replace the EGR, Opti, plugs, fuel fliter. and the fuel pressure regulator. O ya and u have to hold the gas all the way down for the car to start. I also cteaned the TB and IAC.

 

im gonna guess a throttle posistion sensor, put it on a scanner and find out.

 

Like Prorac1 said, when you mash on it with the a/c on, the throtle position sensor should turn the a/c off and give you power.

 

well it dosent do that i just have to hold the pedal to the floor for it to start.

 

not sure on your idle problem, but it sounds like you have a leaky injector(s), put a fuel pressure guage on it and see if the pressure bleeds down, if so pop the fuel rail off and turn the key to the on position and check then.