That is not the direction I was thinking. The Caravan POH has a specific t/o procedure when type II or IV anti-ice fluid has been applied. Use no flaps, and rotate and climb faster than normal. As far as I know, this is a pretty normal procedure for any low speed a/c which has had anti-ice fluid applied. Anti-ice fluid is more viscous than de-ice fluid, and needs high airspeed in order to blow it off of the plane. The special procedure is designed to blow the anti-ice fluid off of the plane before it is trying to fly.

I am aware anti-ice fluid is different than the de-ice fluids we routinely use. De-ice fluid has lower viscosity and isn't supposed to need extra airspeed to blow it off prior to t/o. Having said that, it is not unusual to get de-iced, fly for 40 minutes and still find de-ice fluid residue on some a/c surfaces.

What I am supposing here is a possibility that a small amount of de-ice fluid adhering to the horizontal stabilizer at the point in time when tail force should be switching from down to up is enough to contribute to airflow separation under some circumstances. I think this possibility is all the more plausible when one considers that airflow patterns over the Caravan's tail change radically when tail forces are shifting from down to up. During initial climb out when the tail is producing down force perhaps there are spots on top of the horizontal stabilizer from which the fluid does not blow right off?

Again, I'm not saying de-ice fluid is interfering with tail section airflow, I'm just considering the possibility.