noway ((hugs)) very un mn like but tough shit,i think you need one
i shall give you nearly 20yrs worth of childcare experience - he sounds like a normal 3yr boy
he sounds just like my current dc a year ago and also like my ex dc 7yrs ago
current dc is now 5, but from 18mths or so,he was a rascal, weeks he would be very good then flip, once started nursery, he was also a pain as when home he was bored - didnt help he is the eldest in the year and missed full time school by 2 weeks, so should have really been at school in 2009 sept, but instead when last year when 4yr 11 mths and 2 weeks
always said to mb that if she had given birth on time,instead of being induced 2 weeks late, life would have been easier 
boys go though terrible tantrums,far worse than girls imho
a lot can be boredom, but also sometimes they get so much negative feedback/response, they think fuck it and just behave badly
i would recommend bribery star charts, they really do work or a marble jar when been good/helpful put marbles in, but also when naughty/not doing as told, then take out in front of him
when jar is full he can have a reward, whether a small toy, cheap dvd/cinema etc
give him 5 mins warnings, as when you need to do something, in in 5 mins im going to turn the tv off/you need to get dressed etc - if need be use a buzzer so when the 5 mins up he hears the ringing and knows it is time,as well as you saying to him
i find easier to get dressed before tv personally
i would also say to him that if he behaves like that when you turn it off, then you wont put the tv on and he wont be able to watch anything
when dc used to threw self on floor, mb and i would ignore and walk out of room -he will soon stop if doesnt have an auidence
messsage me anytime you want advice/moan/ear etc x