f150 trans problems
 

ok new to the site..
ok my problem ....i have a 2003 f150 super crew .had a new transsmission and torque converter put in about a yr ago. $4200 with rental fees.. now the problem.. since day one of picking up the truck i have noticed that the truck just dont shift right .. it will not shift into overdrive until i hit 50 mph and as soon as i drop below it drops out back into lower gear causeing rpms to run about 2500rpms ..at highway speeds over 70 mph when i go to make a pass or wot it take for ever for the trans to drop back into overdrive..and for get trying to pull something .. tried to pull a 5x10 uhaul trailer (empty) and wow i could not get the truck to stay in overdrive. it would slip in and out over and over.on a full tank of gas i was able to drive 175 miles before i had to fill up again. i have been back to ford more then a dozen times and no one can figure out the problem.. no codes thrown .. all they keep telling me is trans is doing what its told to do but it seems the coverter is not locking up 100% .they rebuilt the trans and replaced the converter this week and the problem is now worse.. please any help ....... i know this is long but wanted to spell it all out to give a full picture.. thank you