Theoretically, yes a completely broken mount could cause a dive to the right. But simple visual inspection should tell you if there is broken metal or blown rubber on your mounts. I would suspect the brake system for that symptom.
As far how hard is it? Once you've located them all, it should take less than a day to do all the mounts if you have a good floor jack, or better yet, an engine hoist. Big bolts that are tighter than heck, but not that hard to do.
Dave
__________________  '93 Ranger 4X4, '93 Crown Vic, '95 Contour. | 
Motor mount / trans mount 
Linear Mode
