I'm 16 and just bought a new truck I baught it on a warmer day and now that its starting to cool down it seems like it slips in 1st when the trans is cold and only when its cold it also loses 4th when it gets warm after about 15 minutes at 60mph it lose 4th and jumps fron 2500 rpm to 3000 rpm just looking for advice going to change the filter atf and flush the system

 

sounds like your transmission fluid might be cooked. Remove the pan, drain it out, and put some fresh stuff in there through the dipstick tube.