1995 E-150 V6 shifting problems, high shifting?

my 1995 E-150 V6 shifts perfect except after it is really warmed up, and usually does it on a hot day(somedays it won't do it at all) mainly if i get off the highway from over 65, starting back out from a stop it doesn't seem to want to go into 2nd or 3rd easily or shifts at high rpm or when i let off the gas it will shift, when i manually shift it it works fine, could it be shift solenoids? or is there a manual shift lever or sensor or maybe the linkage? any help would be greatly appriciated, I can do simpler work like that myself just would like to diagnose the problem or start out with the cheaper possible fixes first, thanks, Will