The force of metaphors that blunts description: This is partially correct but not comprehensive. Dr. Johnson criticizes the loss of metaphorical force due to overemphasis on details, but this isn't the main fault he highlights.
The mind that goes astray toward the original: This is also partially correct. Dr. Johnson mentions that the mind focuses on the original object rather than the metaphor, but again, this isn't the primary issue he is criticizing.
The metaphysical poets’ tendency to saunter away: This option captures the main idea. "Saunter away" implies a meandering or wandering off, which aligns with pursuing thoughts too far into details and losing the broader view, leading to the loss of grandeur and power in their writing.
The metaphysical insistence on the particular than the general: This is close, but it’s not the tendency to focus on particulars per se that is the fault, but rather their tendency to wander off into details, losing the overall effect.