We just moved across the country also... My four year old hasn't done so great. He is an emotional roller coaster-part of it I know is being four. Never the less it has been driving me crazy (the attitude). I have found a couple of solutions... that have helped. He insists on driving his 2 year old brother crazy also and letting his 2 year old brother get the best of him.
First, we have to be extremly consistent. Food has to be punctual-meals and snacks... He doesn't always say he is hungry but if he is and hasn't said anything he becomes very emotional.
Second, we joined a playgroup that meets once a week a a local park and he doesn't always play with the other kids yet, but it is two hours of park and out door time with brother and I get to know some friends.
Third, we set aside preschool time at home. He loves to work on his numbers, letters, and school work. We have also found a group of moms that do a small preschool- 5 kids meet 2 days a week for two hours each of the days. Between the five moms we take turns teaching the classes and then a helper rotates through too. We have created a curriculium that every three to four week the theme changes along with the teacher. That way as moms we are able to get a little break when we are not teaching or rotating through as teachers helper. You can do this with two kids or more... If you need ideas you can write me.... All of the curriculium we are able to find as free printables online. So the expense is very little. This little class gives a lot of structure to our 4 year olds life and we can afford it.
Forth, We spend a lot of time telling him that it is not okay to talk mean, wine, scream, hit, etc... and send him to time out after one or two warnings.
And finally- when nothing else seems to be working I take both boys out side and make them run. No play ground or toys. We live in an area that has alot of sidewalks in it and I tell them to run and keep me in sight- I am 7 months pregnant so I don't run so well or keep up very well, but by the time we are done running they usually have smiles on their faces. The first time I did this the 4 year old was so cranky that it took about five to ten minutes for him to really warm up to the idea, but when his brother was getting to choose the path of running he decided to participate and enjoyed himeself.
Good luck- We have only been on the east coast for about a month and the adjustment has been more difficult then we expected for the kids- But I know part of it is the ages that they are on top of everything.
L.