Car will not idle on its own. If I hold the throttle it will idle just fine

well if u have to keep the throttle idleing to keep it from dieng,im not a proffesional but a throttle positioning sensore or TPS for short is what keeps track of the throttle position when its in iddle.

More than likey the Auto Idle Control valve (AIC) is what controls the idle. A pintle winds out and in, to allow air to mix as throttle is applied. It may just need spraying with throttle body cleaner or repalcing, cost is about 45 dollars and held on with 2 torx screws about 15 size.

On the right side of your valve cover gasket (easier to see with the air filter and housing removed) you have whats called your cam sensor check for operation of it first.