Hard Starting

I don't think it's your Voltage Reg. With a meter you should have 1.2 Ohms resistance over your resister. Although it may look good, get it checked, their could be cracks ect which have increased the resistance to start correctly...that's why when you jumped it, it started no problem...Also, while jumping it, don't leave that jumper on very long, it's only used for the "start" not "run" circuit as it delivers power straight to the coil in the start position.

A bad Voltage Reg may allow your alt to over charge your battery...are you having battery problems?