if I spend all of my time for an extended period on my mountain bike, my road bike will feel quite awkward for a while. Out of the saddle sprinting on the road bike is worst offender. That's when there's been no real changes to me or my road bike. Saddle setback and height are quite close between my bikes. I really notice the q-factor difference.

Assuming your MTB seat height is dead on correct (and that is a non-trivial assumption), typically, XC mountain bike seat height will be very very slightly lower than road/tri bike seat height.

Since it is your road bike seat height that feels "off", if it were me, I would initially set my road/tri seat height to be the same as my MTB seat height but only after exactly correcting for differences in saddles (if appropriate), pedal stack height (with appropriate shoes engaged) with actual measured road vs MTB shoe insole/outsole/cleat engaged stack heights.

Then, I would very gradually raise my road/tri bike seat height (should be only by a few mm vs your corrected MTB seat height) to what feels comfortable and powerful.

---

Advanced Aero TopTube Storage for Road, Gravel, & Tri...ZeroSlip & Direct-mount, made in the USA.
DarkSpeedWorks.com.....Reviews.....Insta.....Facebook
--

I felt that too, especially with regards to handling, weight, stability.
That aside the actual mechanics of pedaling feel different.

That's fair.
I was under the impression they should be similar, so using all variables for the measurements makes sense.

Interesting.
I think my road shoes are mainly the issue.
When commuting I have been using runners (Kinvara 5's) on flat pedals (b/c of the ice and snow) but my ~7 year old LG tri shoes on the roadie.
Did my same commute as yesterday on the roadie, but this time with the Kinvara's vs the cycling shoes, and it felt infinitely better. Not perfect, but MUCH better.
My foot was more centered on the pedals, as in, the spindle was further back relative to my cycling shoes.
I think 1) cleat position maybe isn't right on the LG shoes and 2) they're just totally beat and in need of replacement.
Getting new cycling shoes may be my first step, and then go from there.