what causes me to start only in nuetral in a 1993 850 glt

You are saying it only starts in Neutral and not Park and Neutral. Sounds like a pad Neutral Safety Switch or one that is out of adjustment. You would have to follow the wiring diagram and test procedures to test the Neutral Safety switch usually mounted on the transmission. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online