First off...the average fox weighs about 8 pounds...Now you can get a big fox too well up to 17 pounds that for sure...Coyotes in Pa the small ones are about 28 pounds and the larger ones go way past 48 pounds to 50 pounds.. Seems like in the Mosquito Creek hunt coyotes over 48 pounds are the ones that place in 1,2,and 3rd place..
Now the 3 inches could be a big fox or a small coyote.
As far as for calling them in with the scenario you use.. They will come to that calling sequence but they have to be there.. Remember unlike fox who live in that home range.. Coyotes travel great distances. The day you called it could be they just were not there..What a gift you get when calling fox and the coyotes howl break in the silence.. Ah they are there and if you quit calling fox then and go to the scenario, done right you could get one to come in.. Remember too...Doing just one thing wrong..Like clicking the forearm of your shotgun, coughing etc..Your coyote hunt could be over before it even started it..
Coyote prints are unique.. I like to think of them like a spear head shape... Many times you will see the two front claws in the track too. Very stream line. Could be that maybe the 3 inch prints could be that of a large red fox?
??or a small coyote...When I looked at the prints you posted I thought for sure they were coyote..