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If you have to open the throttle to get it to start and idle then you may have an issue with the idle air control motor (IAC). The IAC is what lets air into the engine when the throttle is closed, if the IAC doesn't respond correctly then the engine won't run without cracking the throttle.
I would firs make sure the throttle body bore and blade are clean. The IAC's strategy relies on a small amount of air past the throttle blade and carbon buildup will restrict that. Carbon can be cleaned with a rag and some carb cleaner.
If the throttle body is clean or cleaning it doesn't help then turn your attention to the IAC. It could be sluggish or not moving just from age and need to be replaced, or it may be carboned up also. You can try cleaning it before replacing it to see if that helps.