03s and some 04s - the valve spring(s) would break and when they did, it would not idle and you would have to hold the pedal to keep it running. Do a compression check on cylinders to see if a spring is broken and a valve is open

 

I agree with weed, But you can remove the EGR and put a plate over the EGR port and see how it runs. But it maybe a broken valve spring. As weed had said.

 

How can you do a compression check?

 

Go to any auto parts store and buy a compression tester. They do not cost much. Harbor Freight also has them. Unplug the electrical connector from the coil packs and remove all of them with a 10 mm socket. Remove ONE plug from each cylinder. Screw the compression tester into the first cylinder crank the engine over for 5 secs and record the number on the gauge and which cylinder it is. Do this for all cylinders.

Also, you might want to pull the fuse or relay for the fuel pump. Not sure which is it so look on the back of the fuse cover or in the Service Manual. You can find those in the links in my signature

 

Thanks do the 04s have a IAC valve?